JP5439500B2 - Electrostatic protective paste, electrostatic protective component and method for manufacturing the same - Google Patents

Description

  The present invention relates to an electrostatic protection paste, an electrostatic protection component, and a method for manufacturing the same.

  In recent years, electronic devices such as portable information devices have been rapidly reduced in size and functionality. Along with this, miniaturization of electronic components mounted in the electronic device is also progressing rapidly. However, since the withstand voltage of electronic devices and electronic components is reduced by them, for example, electrostatic pulses generated when a terminal of an electronic device comes into contact with a charged human body, or external noise entering from an antenna of a portable information device Due to the overvoltage applied by the electronic device, there is a problem that an electronic circuit (electronic component) inside an electronic device such as a portable information device is destroyed, and the number of occurrences is increasing. Here, the electrostatic pulse and the external noise mean a voltage of several hundred to several kilovolts generated in a time of 1 nanosecond or less.

  Conventionally, as a countermeasure against such an overvoltage caused by electrostatic pulses or external noise, a method of providing a countermeasure component such as a varistor between a line to which the overvoltage is applied and a ground is employed for an electronic device. However, in recent years, the amount of information exchanged in portable information devices has further increased, and accordingly, the quality of signals for exchanging information has been demanded. Therefore, it is required to reduce the stray capacitance and its variation with respect to the countermeasure component.

  In response to such a demand, a varistor generally has a problem in that its capacitance increases because a structure in which, for example, a ceramic film mainly composed of zinc oxide or the like is laminated is applied. Therefore, in order to reduce stray capacitance, it has already been proposed to use an antistatic component (static protection component) having a structure in which an electrostatic protection film is formed between electrodes facing each other through a narrow gap. Specific examples of such anti-static components (electrostatic protection components) include those disclosed in Patent Documents 1 to 8 below.

In Patent Document 1, as a specific material for an electrostatic protection film applied in the structure of an anti-static component, aluminum in which a passivation layer (aluminum oxide) is formed on the surface to ensure high insulation is disclosed. The use of flour is disclosed.
In Patent Document 2, as a material for an electrostatic protection film in an electrostatic protection element, a material which is composed mainly of zinc oxide (ZnO) and doped with a material made of manganese (Mn) or cobalt (Co) to become a semiconductor is disclosed. , Powder composition composed of bismuth (Bi), antimony (Sb), silicon (Si), calcium (Ca), barium (Ba), titanium (Ti) or aluminum (Al), or a minor component composed of these compounds It is disclosed to use a paste formed by mixing a powder such as a powder composition and glass frit.
In Patent Document 3, as a material of an electrostatic absorber in an electrostatic protection element, zinc oxide (ZnO), a powder synthesized by mixing manganese (Mn) and cobalt (Co) for heat treatment and synthesizing the semiconductor, It is disclosed to use a material obtained by heat-mixing a carbide or oxide such as bismuth (Bi) or aluminum (Al) uniformly.
Patent Document 4 discloses forming a bank portion on an electrode in order to flatten the transient voltage protection film in a step of forming a transient voltage protection film by adhering and curing a transient voltage protection material on the electrode. Yes.

In Patent Document 5, as an electrical overload protection material in an electrical overload protection device, an electrostatic protection material composed of an insulating binder, conductive particles, and semiconductor particles, an insulating binder, conductive particles, and semiconductor particles are insulated. Two types of materials are disclosed, which are roughly divided into electrostatic protection materials composed of conductive particles. Patent Document 5 describes that, from the viewpoint of particle size, the former electrostatic protection material has a maximum average particle size of conductive particles less than 10 μm and an average particle size of semiconductor particles less than 10 μm. With respect to the latter electrostatic protection material, the conductive particles have a maximum average particle size of less than 10 μm, the semiconductor particles have an average particle size of less than 10 μm, and the insulating particles have a range of about 200 angstroms to about 1000 angstroms. The average particle size, the conductive particles having a maximum average particle size of less than 10 μm, and the average particle size in the range from about 4 μm to about 8 μm being an average particle size of less than about 4 μm It is also described that there is.
Patent Document 6 discloses a structure in which a gap for separating a first electrode and a second electrode from each other is formed on an insulating substrate, a cavity is formed in the gap, and a voltage variable material is provided in the cavity. An electrical circuit protection device is disclosed. Patent Document 6 discloses the contents related to the thickness of the electrode.
In Patent Document 7, a pair of first electrodes is formed in a thick state using a material having a small specific resistance on an insulating substrate, and a second thin film made of a refractory metal is used between the pair of electrodes. An anti-static component having a structure in which a gap for providing an overvoltage protection material layer is formed in the second electrode is disclosed.
In Patent Document 8, an overvoltage protection material layer is formed between a first ground electrode formed by printing and baking a gold resinate paste on an insulating substrate and a plurality of first upper surface electrodes, and the first ground is formed. An antistatic component having a structure in which a second upper surface electrode covering an electrode and a second ground electrode covering the first ground electrode are formed by printing and baking a conductive paste mainly composed of silver is disclosed.

JP 2007-265713 A JP 2008-294324 A JP 2008-294325 A JP 2001-230046 A Special table 2001-523040 gazette Special table 2002-538601 gazette JP 2009-194130 A JP 2009-147315 A

  An electrostatic protection component having a structure in which an electrostatic protection film is formed between electrodes facing each other through the gap described above, forms at least two electrodes on a ceramic substrate such as alumina so as to face each other through the gap, and then An electrostatic protection film is formed by screen printing or the like so as to cover a part of the electrode and close the gap, and a protective film for protecting the electrostatic protection film from an external environment or the like It is formed so as to cover the entire electrostatic protection film. Further, a nickel plating film and a tin plating film are formed on the electrode portions not covered with the protective film by electroplating in order to improve the reliability as a terminal electrode.

  The conventional materials for forming the electrostatic protection film in the above-mentioned electrostatic protection component are roughly classified into ceramic materials and materials obtained by kneading conductive particles, semiconductor particles, and insulating particles in a resin. The

  Among these, an electrostatic protection component using a ceramic material as the material of the electrostatic protection film has a problem that the variation in capacitance is large. As the cause, it is conceivable that the gap width (electrode spacing) varies greatly for each electrostatic protection component and the dielectric constant variation of the ceramic material is large. That is, assuming that the gap width (electrode spacing) is d, the dielectric constant of the electrostatic protection film is ε, and the sectional area of the electrode is A, the electrostatic capacitance Cp of the electrostatic protection component can be expressed by εA / d. When the gap width d and the dielectric constant ε vary greatly, the variation of the capacitance Cp also increases.

  In addition, when mixing three kinds of materials, conductive particles, semiconductor particles, and insulating particles, into the binder resin, surface treatment for providing a passive layer on the surface of the conductive particles and doping the insulating particles with other substances When special processing such as processing is performed, the electrostatic protection paste becomes expensive, leading to an increase in the cost of electrostatic protection components.

  Furthermore, in an electrostatic protection component using a ceramic material as an electrostatic protection film material, the temperature at which the ceramic material is heat-treated is 1000 ° C. to 1300 ° C. depending on the formation conditions, so that the heat treatment apparatus is large and expensive. There is also.

  Accordingly, in view of the above circumstances, an object of the present invention is to provide an electrostatic protection paste that is inexpensive and can reduce variation in capacitance, an electrostatic protection component using the paste, and a method of manufacturing the same. To do.

The paste for electrostatic protection of the first invention that solves the above problems is an electrostatic protection paste for forming an electrostatic protection film of an electrostatic protection component, and comprises three components of silicone resin, aluminum powder, and zinc oxide powder. are those mixed, whereas the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, 1 6 0 part by weight The aluminum powder has an average particle size of 3.0 to 3.6 μm, and the zinc oxide powder is distributed in a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. To do.

According to a second aspect of the present invention, there is provided an electrostatic protection component comprising: an insulating substrate; a surface electrode formed on the insulating substrate and facing the gap through a gap; and an electrostatic protection film formed in the gap and connected to the surface electrode In the electrostatic protection component having the above, the electrostatic protection film is a mixture of three components of silicone resin, aluminum powder, and zinc oxide powder, whereas the silicone resin is 100 parts by weight. Te, wherein the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight, the aluminum powder has an average particle size of 3.0 to 3. The zinc oxide powder has a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm.

The method for manufacturing an electrostatic protection component of the third invention includes a step of forming a surface electrode by applying an electrode paste onto an insulating substrate and patterning by a screen printing method, and a step of firing the surface electrode. And cutting the fired surface electrode to form a gap, and the surface electrode is opposed to the gap through the gap, and the conductive paste is opposed to the gap through the screen printing method. By applying and patterning to each of the front electrodes, forming a top electrode, and applying a pattern to the gap by applying an electrostatic protection paste to the gap by screen printing, thereby protecting the gap from electrostatic discharge. Forming a film, connecting the electrostatic protection film to a surface electrode facing the gap through the gap, and the upper electrode and the electrostatic protection film. In the method of manufacturing an electrostatic protection component, the paste for electrostatic protection is a mixture of three components of silicone resin, aluminum powder, and zinc oxide powder, and the silicone resin is 100 weights. whereas a part, said aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight, the aluminum powder has an average particle size The zinc oxide powder has a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm.

According to the electrostatic protection paste of the first invention, the electrostatic protection paste of the first invention is an electrostatic protection paste for forming an electrostatic protection film of an electrostatic protection component, and comprises a silicone resin, aluminum powder, it is obtained by mixing the three components of zinc oxide powder, wherein while the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight More than 1 60 parts by weight, the aluminum powder has an average particle size of 3.0 to 3.6 μm, the zinc oxide powder has a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. It is characterized by the fact that only two types of aluminum powder and zinc oxide powder are mixed with the silicone resin that is the binder, and the aluminum powder and zinc oxide powder are special. Since is not subjected such surface treatment, it is possible to realize an inexpensive electrostatic protection paste. Therefore, an electrostatic protection component having an electrostatic protection film formed using this electrostatic protection paste is also inexpensive.
Further, by forming the electrostatic protection film using this electrostatic protection paste, the variation in the dielectric constant of the electrostatic protection film is reduced, so that the variation in the electrostatic capacitance of the electrostatic protection component having the electrostatic protection film is also reduced. . Therefore, when this electrostatic protection component is applied to an electronic device such as a portable information device as a countermeasure against electrostatic pulses or external noise, the stray capacitance and the variation regarding the electrostatic protection component can be reduced.
Further, by using an inexpensive material such as aluminum powder or zinc oxide powder, an electrostatic protection paste can be manufactured at low cost.
In addition, an electrostatic protection component having an electrostatic protection film formed using the present electrostatic protection paste has an ESD (Electrostatic discharge) suppression peak voltage of 500 V or less and a leakage current of 10 μA whose ESD resistance (20 times voltage application) is a standard value. The following target value (insulation resistance R = 3 MΩ or more) can be satisfied.

According to the electrostatic protection component of the second invention, the insulating substrate, the surface electrode formed on the insulating substrate and facing each other through the gap, and the static electricity formed in the gap and connected to the surface electrode In the electrostatic protection component having a protective film, the electrostatic protective film is a mixture of three components of silicone resin, aluminum powder, and zinc oxide powder, and the silicone resin is 100 parts by weight. respect, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight, the aluminum powder has an average particle size of 3.0 to The zinc oxide powder has a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm and is distributed in a silicone resin as an electrostatic protection film binder. An electrostatic protection film is formed of a material that is a mixture of only two types of aluminum powder and zinc oxide powder, and since no special surface treatment is applied to the aluminum powder and zinc oxide powder, the electrostatic protection film is inexpensive. An electrostatic protection component having this electrostatic protection film can also be formed at a low cost.
Moreover, since the variation in the dielectric constant of the electrostatic protection film is reduced, the variation in the capacitance of the electrostatic protection component having the electrostatic protection film is also reduced. Therefore, when this electrostatic protection component is applied to an electronic device such as a portable information device as a countermeasure against electrostatic pulses or external noise, the stray capacitance and the variation regarding the electrostatic protection component can be reduced.
Further, by using an inexpensive material such as the aluminum powder or zinc oxide powder, the electrostatic protection film can be formed at a low cost.
In addition, an electrostatic protection component having an electrostatic protection film formed using the present electrostatic protection paste has an ESD suppression peak voltage of 500 V or less and an ESD resistance of a standard value leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more). The target value can be satisfied.

According to the method for manufacturing an electrostatic protection component of the third invention, a step of forming a surface electrode by applying an electrode paste on an insulating substrate and patterning by a screen printing method, and firing the surface electrode A step of cutting the surface electrode that has been baked to form a gap, and a structure in which the surface electrode is opposed to the gap through the gap. By applying and patterning each of the facing front electrodes, patterning by applying an electrostatic protection paste to the gap by a step of forming the upper electrode and screen printing, and forming the pattern in the gap. Forming an electrostatic protection film, connecting the electrostatic protection film to a surface electrode facing the gap through the gap, and the upper electrode and the electrostatic protection In the method of manufacturing an electrostatic protection component including the step of simultaneously baking, the electrostatic protection paste is a mixture of three components of a silicone resin, an aluminum powder, and a zinc oxide powder. whereas parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, 1 6 0 or less parts by weight, said aluminum powder has an average particle size Is 3.0 to 3.6 μm, and the zinc oxide powder is characterized by having a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. Therefore, the following effects can be obtained. .
That is, since the mechanical strength of the front electrode can be reinforced by the upper electrode, it is easy to form an electrostatic protection film by screen printing.
In addition, since the upper electrode is screen-printed first and then the electrostatic protection film is screen-printed, the electrostatic protection film is screen-printed first, and then the upper electrodes 6a and 6b are screen-printed. The number of times the screen mesh comes into contact with the membrane can be reduced. For this reason, it is possible to reduce the possibility that the electrical characteristics of the electrostatic protection film deteriorate due to the generation of static electricity that is larger than the desired static electricity resistance for the electrostatic protection film due to the charging of the screen mesh during screen printing.
In addition, only two kinds of aluminum powder and zinc oxide powder are mixed in the silicone resin as a binder, and the aluminum powder and zinc oxide powder are not subjected to special surface treatment, so it is cheaply protected against static electricity. An electrostatic protection film can be formed by the paste for use, and an electrostatic protection component having this electrostatic protection film is also inexpensive.
Further, by forming the electrostatic protection film using this electrostatic protection paste, the variation in the dielectric constant of the electrostatic protection film is reduced, so that the variation in the electrostatic capacitance of the electrostatic protection component having the electrostatic protection film is also reduced. . Therefore, when this electrostatic protection component is applied to an electronic device such as a portable information device as a countermeasure against electrostatic pulses or external noise, the stray capacitance and the variation regarding the electrostatic protection component can be reduced.
In addition, the electrostatic protection film can be formed by an electrostatic protection paste using an inexpensive material such as the aluminum powder or the zinc oxide powder.
In addition, an electrostatic protection component having an electrostatic protection film formed using the present electrostatic protection paste has an ESD suppression peak voltage of 500 V or less and an ESD resistance of a standard value leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more). The target value can be satisfied.

It is sectional drawing (BB sectional view taken on the line of FIG. 2) which shows the structure of the electrostatic protection component which concerns on the embodiment of this invention. It is a top view (A direction arrow view of FIG. 1) which shows the structure of the electrostatic protection component which concerns on the example of embodiment of this invention. It is a flowchart which shows the manufacturing process of the electrostatic protection component which concerns on the embodiment of this invention. It is 1st explanatory drawing of the manufacturing process of the electrostatic protection component which concerns on the embodiment of this invention. It is 2nd explanatory drawing of the manufacturing process of the electrostatic protection component which concerns on the embodiment of this invention. It is 3rd explanatory drawing of the manufacturing process of the electrostatic protection component which concerns on the embodiment of this invention. Electrostatic protection when 100 parts by weight of the silicone resin as the binder does not contain zinc oxide and the weight parts (parameters) of the aluminum powder are 95 parts by weight / 160 parts by weight / 200 parts by weight / 250 parts by weight. It is a graph which shows the measurement result of ESD suppression peak voltage (number of times of application 1 time) of components. When the binder silicone resin is 100 parts by weight, the aluminum powder is 160 parts by weight, and the zinc oxide powder parts by weight (parameters) are 0 parts by weight, 40 parts by weight, 80 parts by weight, and 120 parts by weight. It is a graph which shows the insulation resistance deterioration number of the electrostatic protection component of. When the binder silicone resin is 100 parts by weight, the aluminum powder is 160 parts by weight, and the zinc oxide powder parts by weight (parameters) are 0 parts by weight, 40 parts by weight, 80 parts by weight, and 120 parts by weight. It is a table | surface which shows the measurement result of the electrostatic capacitance of this electrostatic protection component. It is the table | surface which compared the electrostatic capacitance of the electrostatic protection component of this invention, and the electrostatic capacitance of the electrostatic countermeasure component of a comparative example. It is the graph which compared the electrostatic capacitance of the electrostatic protection component of this invention with the electrostatic capacitance of the electrostatic countermeasure component of a comparative example. With respect to 100 parts by weight of the silicone resin as the binder, the parts by weight (parameters) of the zinc oxide powder are 60 parts by weight, 80 parts by weight, 120 parts by weight, 160 parts by weight, and 200 parts by weight. Parameter) is 40 parts by weight, 60 parts by weight, 100 parts by weight, 150 parts by weight, 200 parts by weight, and 240 parts by weight. It is a table | surface which shows the result of having confirmed the leakage current of the ESD protection component formed by applying ESD, and the ESD suppression peak voltage. It is sectional drawing which shows the other structure of the electrostatic protection component which concerns on the example of embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  First, based on FIG.1 and FIG.2, the structure of the electrostatic protection component which concerns on the embodiment of this invention is demonstrated.

  The electrostatic protection component shown in FIGS. 1 and 2 is a surface mounting component for surface mounting on a printed circuit board, and an electronic circuit (electronic component) mounted on the printed circuit board is protected from an overvoltage caused by electrostatic pulses or external noise. For protection, it is provided between the line to which the overvoltage is applied and the ground.

  As shown in FIGS. 1 and 2, front electrodes 2a and 2b are formed on the front surface 1a of the ceramic substrate 1 which is an insulating substrate, and back electrodes 3a and 3b are formed on the back surface 1b of the ceramic substrate 1. Yes. The front electrodes 2a and 2b are formed over the entire length of the substrate surface 1a, while the back electrodes 3a and 3b are formed at both ends of the substrate back surface 1b.

  A gap (narrow portion) 4 is formed in the central portion of the substrate surface 1a (between the surface electrodes 2a and 2b). That is, the surface electrodes 2 a and 2 b are opposed to each other with the gap 4 interposed therebetween. The gap 4 is formed by cutting the surface electrode film by a laser method or the like, and has a width d of about 10 μm (7 μm in this embodiment).

  An electrostatic protection film 5 is formed in the gap 4, and the surface electrodes 2 a and 2 b and the electrostatic protection film 5 are connected. That is, the electrostatic protection film 5 is formed between the front electrodes 2a and 2b facing each other through the gap 4. In the illustrated example, the electrostatic protection film 5 is not only formed in the gap 4 but also partially overlapped with the surface electrodes 2a and 2b. That is, the electrostatic protection film 5 has a central portion 5c provided in the gap 4 and both side portions 5a and 5b superimposed on the end portions 2a-1 and 2b-1 of the surface electrodes 2a and 2b, respectively. Note that the protective function against static electricity can be exhibited only by providing the electrostatic protection film 5 in the gap 4.

In the electrostatic protection component of this embodiment, the electrostatic protection film 5 is formed of a material obtained by mixing two kinds of conductive particles and insulating particles in a silicone resin as a binder. . Conductive particles and insulating particles are not subjected to special treatment such as surface treatment such as providing a passive layer on the surface of conductive particles, or treatment such as doping other materials on the surface of insulating particles. Is.
The conductive particles are aluminum (Al) powder that is conductive metal particles, and the insulating particles are zinc oxide (ZnO) powder. As the zinc oxide powder, JIS standard type 1 zinc oxide, that is, zinc oxide having a volume resistivity of 200 MΩcm or more is used. Further, the mixing ratio of the three components of silicone resin, aluminum powder and zinc oxide powder is, for example, 100 parts by weight of silicone resin, 60 to 200 parts by weight of aluminum powder, and 60 parts by weight of zinc oxide powder. Parts to 160 parts by weight. The blending ratio of the electrostatic protection paste satisfies the target value that the ESD suppression peak voltage is 500 V or less, and the ESD tolerance (20 times voltage application) is the standard value leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more). is there. The ESD suppression peak voltage is a voltage generated at the start of discharge. Moreover, the detail about the search of the said mixture ratio is mentioned later.

  Upper electrodes 6a and 6b are formed on the surface electrodes 2a and 2b, respectively. Since the surface electrodes 2a and 2b are thin films, the mechanical strength is reinforced by forming the upper electrodes 6a and 6b on the surface electrodes 2a and 2b. However, the upper electrodes 6a and 6b are formed so as not to contact the electrostatic protection film 5 (at a position away from the electrostatic protection film 5). The reason is that when the upper electrodes 6a and 6b are in contact with the electrostatic protection film 5, when an overvoltage due to electrostatic pulses or the like is applied to the electrostatic protection component, not between the surface electrodes 2a and 2b but between the upper electrodes 6a and 6b. Or the upper electrodes 6a, 6b and the surface electrodes 2a, 2b may start to discharge, and in that case, the original electrostatic protection function of the electrostatic protection component cannot be exhibited. is there.

  The electrostatic protection film 5 is covered with an intermediate layer 7, and the intermediate layer 7 is covered with a protective film 8. Further, both end portions 8a and 8b of the protective film 8 are overlapped with part of the upper electrodes 6a and 6b (portions on the gap side), respectively. The protective film 8 is excellent in moisture resistance and the like, and is provided to protect the electrostatic protective film 5 and the like from the external environment such as humidity. However, since the protective film 8 has insufficient heat resistance, the electrostatic protective film 5 that generates heat during discharge is not directly covered with the protective film 8, and the intermediate protective layer 7 is excellent in heat resistance. The intermediate layer 7 is covered and covered with a protective film 8.

  End face electrodes 9a, 9b are formed on both end faces 1c, 1d of the ceramic substrate 1, and the front electrodes 2a, 2b and the back electrodes 3a, 3b are electrically connected by the end face electrodes 9a, 9b. The end portions 9a-1, 9a-2, 9b-1, 9b-2 of the end surface electrodes 9a, 9b are connected to the end portions 2a-2, 2b-2 of the front electrodes 2a, 2b and the back electrodes 3a, 3b. Since they are respectively superimposed on the end portions 3a-1 and 3b-1, the connection between the end surface electrodes 9a and 9b and the front electrodes 2a and 2b and the back electrodes 3a and 3b is more reliable.

  Furthermore, nickel (Ni) plating films 10a and 10b and tin (Sn) plating films 11a and 11b are formed in this order in order to improve the reliability of the terminal electrodes with respect to the end face electrodes 9a and 9b. ing. The nickel plating films 10a and 10b cover the end face electrodes 9a and 9b, the back electrodes 3a and 3b, the front electrodes 2a and 2b, and the upper electrodes 6a and 6b, respectively, and the tin plating film 11a. 11b cover the nickel plating films 10a and 10b, respectively.

Next, a method for manufacturing an electrostatic protection component according to this embodiment will be described with reference to FIGS. The manufacturing steps (steps) in the flowchart of FIG. 4A to 4D, FIG. 5A to FIG. 5D, and FIG. 6A to FIG. 6C sequentially show the manufacturing state of the electrostatic protection component in each manufacturing process. ing.
In this embodiment, a 1005 type electrostatic protection component (having a width W of 0.5 mm and a length L of 1.0 mm shown in FIG. 2) was manufactured.

In the first step (step S1), as shown in FIG. 4A, the ceramic substrate 1 is received in a manufacturing process (not shown) of the electrostatic protection component. Here, an alumina substrate was used as the ceramic substrate 1. This alumina substrate is manufactured using 96% alumina as a ceramic material.
FIG. 4A shows only one ceramic substrate 1 in one piece area corresponding to one piece of electrostatic protection component, but the actual ceramic substrate 1 before being primarily divided in step S13. Is a sheet-like shape in which a plurality of primary slits and secondary slits are formed vertically and horizontally, and a plurality of individual regions are connected vertically and horizontally.

  In the next step (step S2), the back electrodes 3a and 3b are formed on the back surface 1b of the ceramic substrate 1 as shown in FIG. The back electrodes 3a and 3b are formed by applying and patterning an electrode paste on the substrate back surface 1b by screen printing. Here, a silver (Ag) paste was used as the electrode paste. The screen printed back electrodes 3a and 3b are dried to evaporate the solvent in the electrode paste.

  In the next step (step S3), as shown in FIG. 4C, the surface electrode 2 (film for forming the surface electrodes 2a and 2b later) is formed on the surface 1a of the ceramic substrate 1. The front electrode 2 is formed by applying an electrode paste to the substrate surface 1a and patterning it by screen printing. Here, a gold resinate paste was used as the electrode paste. The screen-printed front electrode 2 is dried to evaporate the solvent in the electrode paste.

  In addition, as an electrode paste for forming the surface electrode 2, a resinate paste (metal organic paste) other than gold can be used. For example, a resinate paste of platinum (Pt) or silver (Ag) can be used. As an electrode paste for forming the back electrodes 3a, 3b, a silver / palladium (Ag / Pd) paste may be used.

  In the next step (step S4), the back electrodes 3a and 3b formed in step S2 and the front electrode 2 formed in step S3 are simultaneously fired at 850 ° C. for 40 minutes.

  In the next step (step S5), as shown in FIG. 4D, the center portion of the surface electrode 2 baked in step S4 is cut by a laser method using a laser having a UV wavelength region (not shown). Thus, a gap (narrow portion) 4 is formed. Here, a third harmonic laser (wavelength: 355 nm) was used as a laser having a UV wavelength region. The width d of the gap 4 was 7 μm. As a result of forming the gap 4, the pair of front electrodes 2 a and 2 b face each other through the gap 4.

In the next step (step S6), as shown in FIG. 5A, a conductive paste is applied to each of the surface electrodes 2a and 2b by a screen printing method to form a pattern. Upper electrodes 6a and 6b are formed on 2b. The number of screen printings at this time is one. The upper electrodes 6a and 6b are formed so as to overlap the surface electrodes 2a and 2b at positions away from the electrostatic protection film 5 so as not to contact the electrostatic protection film 5. The upper electrodes 6a and 6b after screen printing are dried to evaporate the solvent in the conductive paste.
The screen mesh used in this screen printing has a mesh size of 400 and an emulsion thickness of 82 μm (product number: st400).
In addition, as the conductive paste, a paste obtained by kneading silver powder and an epoxy resin was used. However, the present invention is not limited thereto, and a thick film electrode paste obtained by kneading nickel (Ni), copper (Cu) powder, and the like and an epoxy resin may be used as the conductive paste for the upper electrode.

  In the next step (step S7), as shown in FIG. 5B, the electrostatic protection paste is applied to the gap 4 and the surface electrodes 2a and 2b by a screen printing method and patterned to thereby protect the static electricity. A film 5 is formed. The electrostatic protection film 5 is formed in the gap 4 and connected to the surface electrodes 2a and 2b (that is, interposed between the surface electrodes 2a and 2b), and is partially overlapped with the surface electrodes 2a and 2b. The electrostatic protection film 5 after screen printing is dried at 100 ° C. for 10 minutes to evaporate the solvent in the electrostatic protection paste.

The screen mesh used in this screen printing is a calendar mesh, which has a mesh size of 400, a wire diameter of 18 μm, and an emulsion thickness of 52 μm (product number: cal400 / 18).
The paste for electrostatic protection used here uses a silicone resin binder as a basic material, and this silicone resin is kneaded with two types of powder, aluminum powder used as conductive particles and zinc oxide powder used as insulating particles. It is a thing. Furthermore, the compounding ratio of these three components was 100 parts by weight of the silicone resin, 160 parts by weight of the aluminum powder, and 120 parts by weight of the zinc oxide powder. In this case, the ESD suppression peak voltage is 500 V or less, and the ESD tolerance satisfies the target value of a leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more) with a standard value.

As the silicone resin, an addition reaction type silicone resin having a volume resistivity of 2 × 10 ¹⁵ Ωcm and a dielectric constant of 2.7 was used.
As the aluminum powder, aluminum powder having an average particle size of 3.0 to 3.6 μm obtained by melting aluminum, spraying at high pressure and solidifying by cooling was used.
As the zinc oxide powder, zinc oxide having JIS standard type 1 insulation (volume resistivity of 200 MΩcm or more) was used. In addition, zinc oxide powder having a particle size distribution of 0.3 to 1.5 μm, an average particle size of 0.6 μm, and a primary aggregation particle size of 1.5 μm is applied to the zinc oxide powder. did.

  In the next step (step S8), the upper electrodes 6a and 6b formed in step S6 and the electrostatic protection film 5 formed in step S7 are simultaneously baked at 200 ° C. for 30 minutes.

In the next step (step S9), as shown in FIG. 5 (c), a silicone resin paste is applied to the electrostatic protection film 5 and the surface electrodes 2a and 2b by a screen printing method and patterned. An intermediate layer 7 that covers the protective film 5 and the like is formed. The number of screen printings at this time is one.
Here, a silicone resin paste containing 40 to 50% silica was used as the silicone resin paste.
The screen mesh used in this screen printing is a calendar mesh having a mesh size of 400, a wire diameter of 18 μm, and an emulsion thickness of 52 μm (product number: cal400 / 18).

  In the next step (Step S10), the intermediate layer 7 formed in Step S9 is baked at 150 ° C. for 30 minutes.

In the next step (step S11), as shown in FIG. 5 (d), the epoxy resin paste is applied to the intermediate layer 7, the surface electrodes 2a and 2b, and the upper electrodes 6a and 6b by a screen printing method to form a pattern. Thus, the protective film 8 that covers the intermediate layer 7 and the like is formed. The number of screen printings at this time is two.
The screen mesh used in this screen printing has a mesh size of 400 and an emulsion thickness of 102 μm (product number: 3DSus400 / 19).

  In the next step (step S12), the protective film 8 formed in step S11 is baked at 200 ° C. for 30 minutes.

  In the next step (step S13), the ceramic substrate 1 is primarily divided along the primary slit formed in the sheet-like ceramic substrate 1. As a result, the ceramic substrate 1 has a strip shape in which a plurality of individual regions are arranged in a horizontal line, and end faces 1c and 1d are generated.

In the next step (step S14), as shown in FIG. 6A, the conductive paste is transferred to the end surfaces 1c and 1d of the ceramic substrate 1, a part of the front electrodes 2a and 2b, the back electrode 3a, by a transfer method. It is applied to a part of 3b, and this is baked at 200 ° C. for 30 minutes in the next step (step S15), thereby forming end face electrodes 9a and 9b. At this time, the end face electrodes 9a and 9b are partially overlapped with the front electrodes 2a and 2b and the back electrodes 3a and 3b, and electrically connect the front electrodes 2a and 2b to the back electrodes 3a and 3b.
Here, a paste obtained by kneading silver powder and an epoxy resin was used as the conductive paste.

  In the next step (step S <b> 16), the ceramic substrate 1 is secondarily divided along the secondary slit formed in the belt-shaped ceramic substrate 1. As a result, the ceramic substrate 1 is divided into individual pieces to form individual pieces.

  In the next step (step S17), as shown in FIG. 6B, end face electrodes 9a and 9b, back electrodes 3a and 3b, part of front electrodes 2a and 2b, and upper electrode are formed by barrel plating. Electroplating is performed on part of 6a and 6b to form nickel plating films 10a and 10b.

  In the last step (step S18), as shown in FIG. 6C, the tin plating films 11a and 11b are electroplated on the nickel plating films 10a and 10b formed in step S17 by a barrel plating method. Form.

  Next, the search for the blending ratio of the electrostatic protection paste will be described with reference to FIGS.

  As target values for determining the blending ratio of the electrostatic protection paste, the ESD suppression peak voltage of the electrostatic protection component was set to 500 V or less, and the ESD resistance was set to a standard value leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more). .

  First, the weight part of the aluminum powder of the conductive metal particle suitable for mixing in the silicone resin as the binder was searched.

  95 parts by weight, 160 parts by weight, 200 parts by weight, 250 parts by weight of aluminum powder, which is conductive metal particles having an average particle diameter of 3.0 μm, are mixed with 100 parts by weight of the silicone resin as a binder to protect against static electricity. A paste was produced. And each ESD protection component (the manufacturing process is as above) which has each ESD protection film 5 formed using the paste for ESD protection from which the weight part of these aluminum powders differs, and performs ESD test, ESD suppression peak The voltage was measured.

  As shown in the test results in FIG. 7, each of the electrostatic protection components does not contain zinc oxide and increases the mixing amount of aluminum powder in the order of 95 parts by weight, 160 parts by weight, 200 parts by weight, and 250 parts by weight. ESD suppression peak voltages of 550V, 450V, 400V, and 300V were shown, respectively. The number of times of voltage application at this time is one. From this test result, in order to satisfy the target value of ESD suppression peak voltage of 500 V or less, the mixing amount of aluminum powder of conductive metal particles having an average particle size of 3.0 μm was set to 160 parts by weight.

  However, when the number of times of voltage application is increased, the ESD suppression peak voltage of the electrostatic protection component is lowered due to the insulation resistance deterioration of the electrostatic protection film 5, and the ESD tolerance of the electrostatic protection component is not good. For example, when the aluminum powder is 160 parts by weight, the ESD suppression peak voltage was 450 V. However, the insulation resistance of the electrostatic protection film 5 deteriorates after the voltage application (the insulation resistance does not recover), and the leakage current is 10 μA or less ( The target value of insulation resistance R = 3 MΩ or more) could not be satisfied. In this case, the ESD suppression peak voltage is lower than 450V for the second and subsequent voltage application. Therefore, as a countermeasure against the ESD suppression peak voltage drop due to the deterioration of the insulation resistance, zinc oxide powder, which is insulating particles, was also mixed, and the weight part thereof was searched.

  100 parts by weight of the silicone resin as the binder, 160 parts by weight of the aluminum powder, and furthermore, as a countermeasure for lowering the ESD suppression peak voltage, insulating particles having a volume resistivity of 200 MΩcm or more are used as an average particle diameter. The paste for electrostatic protection which knead | mixed zinc oxide powder which is 1.5 micrometer 5 weight part, 15 weight part, 40 weight part, 60 weight part, 80 weight part, 100 weight part, 120 weight part was manufactured, respectively. And each ESD protection part (manufacturing process is as above) which has each ESD protection film 5 formed using the paste for ESD protection from which the weight part of these zinc oxide powders is different, and performs ESD test, and ESD protection It was confirmed whether or not the insulation resistance of the film 5 deteriorated. Regardless of the weight part of zinc oxide powder, the number of tests of the electrostatic protection component is 30. In addition, this ESD test was implemented also about the case where the mixing amount of zinc oxide powder is 0 weight part.

As a result, as the weight part of the zinc oxide powder is increased, the electrostatic protection component whose insulation resistance of the electrostatic protection film 5 has deteriorated, that is, the target value of leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more) cannot be satisfied. The number of electrostatic protection parts (hereinafter referred to as insulation resistance deterioration number) has decreased. Note that the target value of the ESD suppression peak voltage of 500 or less was satisfied regardless of the weight part of the zinc oxide powder. FIG. 8 shows the test results when the amount of zinc oxide powder mixed is 0, 40, 80, and 120 parts by weight.
As shown in FIG. 8, when the mixing amount of zinc oxide powder was 120 parts by weight, the number of deterioration of the insulation resistance of the electrostatic protection component by the ESD test was zero. That is, none of the 30 electrostatic protection components cause a decrease in the ESD suppression peak voltage due to the deterioration of the insulation resistance of the electrostatic protection film 5.

In addition, for each electrostatic protection component in which the amount of zinc oxide powder mixed is 0, 5, 15, 40, 60, 80, 100, 120 parts by weight. A measurement test of the capacitance Cp was also conducted. As a result of this measurement test, it was confirmed that all the electrostatic protection components had small variations in the capacitance Cp. FIG. 9 shows test results when the amount of zinc oxide powder mixed is 0, 40, 80, and 120 parts by weight. Regardless of the weight part of the zinc oxide powder, the difference between the maximum value and the minimum value of the capacitance Cp is small, and the variation in the capacitance Cp is small.
As described above, the variation in the electrostatic capacitance Cp of the electrostatic protection component is small because the gap 4 is formed by cutting the thin-film surface electrode 2 by a laser method or the like, so that the cross-sectional areas A and gaps of the surface electrodes 2a and 2b In addition to the small variation in the width d, the variation in the dielectric constant ε of the electrostatic protection film 5 formed using the above-mentioned electrostatic protection paste is also a factor.

  10 and 11 show the static electricity of the electrostatic protection component of the present invention (an example of using an electrostatic protection paste of 100 parts by weight of silicone resin, 160 parts by weight of aluminum powder, and 120 parts by weight of zinc oxide powder). A comparison between the capacitance Cp and the capacitance Cp of the comparative example (varistor) is shown. This comparison also shows that the electrostatic protection component of the present invention has a small variation in the capacitance Cp.

  Furthermore, in FIG. 12, regarding the blending ratio of the three components of the silicone resin, the aluminum powder, and the zinc oxide powder constituting the electrostatic protection paste, 100 parts by weight of the silicone resin as the binder with respect to 100 parts by weight of the zinc oxide powder ( Parameter) is 60 parts by weight, 80 parts by weight, 120 parts by weight, 160 parts by weight, 200 parts by weight, and 40 parts by weight, 60 parts by weight, 100 parts by weight, 150 parts by weight, 200 parts by weight of aluminum powder. Results of confirming the screen printability when forming an electrostatic protection film in the case of parts by weight and 240 parts by weight, and the leakage current and ESD suppression peak voltage of an electrostatic protection component formed by applying the electrostatic protection film in those cases Indicates.

  In FIG. 12, “printability” refers to a state when the electrostatic protection film 5 is screen-printed using an electrostatic protection paste of each blending ratio. Regarding the printability, “XX” indicates that blurring occurs in the electrostatic protection film 5, and “X” indicates that blurring occurs in the electrostatic protection film 5. In these cases, it is determined to be defective.

  Moreover, in FIG. 12, the leakage current and the ESD suppression peak voltage are as compared with each electrostatic protection component (manufacturing process is as described above) having each electrostatic protection film 5 formed using the electrostatic protection paste of each blending ratio. It is the result of conducting an ESD test and measuring the leakage current and the ESD suppression peak voltage. Regarding the leakage current, “×” indicates a case where the number of electrostatic protection components that did not satisfy the target value of the leakage current of 10 μA or less was 2 or more out of 10. In this case, it is determined to be defective. In addition, “△” indicates that the number of electrostatic protection components that did not satisfy the target value of the leakage current of 10 μA or less was one in ten, and “◯” indicates that the electrostatic protection that did not satisfy the target value of the leakage current of 10 μA or less. This is a case where the number of parts is 0 out of 10. Regarding the ESD suppression peak voltage, “×” indicates a case where the number of electrostatic protection components that did not satisfy the target value of the ESD suppression peak voltage 400V to 500V was 2 or more out of 10. In this case, it is determined to be defective. “△” indicates the target value of the ESD suppression peak voltage 400V to 500V when the number of electrostatic protection components that did not satisfy the target value of the ESD suppression peak voltage 400V to 500V is one in ten. This is the case where the number of electrostatic protection components that did not satisfy the above is 0 out of 10.

  From FIG. 12, the compounding ratio of the three components is that the silicone resin is 100 parts by weight, whereas the aluminum powder is in the range of 60 parts by weight to 200 parts by weight, and the zinc oxide powder is 60 parts by weight to 160 parts by weight. It turns out that the range is sufficient. More desirably, the blending ratio of the three components is 100 parts by weight of the silicone resin, while the aluminum powder is in the range of 60 parts by weight to 200 parts by weight, and the zinc oxide powder is 120 parts by weight to 160 parts by weight. It turns out that the range is sufficient. In addition, it has also been confirmed that the electrostatic protection parts to which these mixing ratios are applied have small variations in electrostatic capacity.

As described above, according to the present embodiment, the electrostatic protection paste is formed by kneading only two kinds of conductive particles and insulating particles in a silicone resin as a binder. Since the conductive particles and the insulating particles are not specially treated, they are inexpensive. Therefore, the electrostatic protection component having the electrostatic protection film 5 formed using this electrostatic protection paste is also inexpensive.
Moreover, since the variation in the dielectric constant ε of the electrostatic protection film 5 is reduced by forming the electrostatic protection film 5 using this electrostatic protection paste, the electrostatic capacity Cp of the electrostatic protection component having the electrostatic protection film 5 is reduced. The variation of the is also reduced. Therefore, when this static electricity protection component is applied to an electronic device such as a portable information device as a countermeasure against static electricity pulses or external noise, the stray capacitance and the variation of the static electricity protection component can be reduced in the electronic device.
In addition, the conductive particles are aluminum powder, and the insulating particles are zinc oxide powder. Since these aluminum powder and zinc oxide powder are inexpensive materials, an electrostatic protection paste can be manufactured at low cost. Can do.
Further, the blending ratio of the three components of the electrostatic protection paste is such that the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight to 200 parts by weight, and the zinc oxide powder is 60 parts by weight to 160 parts by weight. Parts (more desirably 120 parts by weight to 160 parts by weight), the electrostatic protection component having the electrostatic protection film 5 formed using this electrostatic protection paste has an ESD suppression peak voltage of 500 V or less and an ESD resistance. The target value of a standard value leakage current of 10 μA or less (insulation resistance R = 3 MΩ or more) can be satisfied.

  Further, according to the present embodiment, the screen-printed upper electrodes 6a and 6b and the electrostatic protection film 5 are simultaneously baked, so that the manufacturing process is simplified and the electrostatic protection component is manufactured at a low cost. can do.

Furthermore, since the upper electrodes 6a and 6b are screen-printed first and then the electrostatic protection film 5 is screen-printed thereafter, the following effects can be obtained.
That is, since the mechanical strength of the front electrodes 2a and 2b can be reinforced by the dried upper electrodes 6a and 6b, it is easy to form the electrostatic protection film 5 by screen printing.
In addition, the number of times the screen mesh contacts the electrostatic protection film 5 can be reduced as compared with the case where the electrostatic protection film 5 is screen-printed first and then the upper electrodes 6a and 6b are screen-printed. To reduce the possibility that the electrical characteristics of the electrostatic protection film 5 will deteriorate due to the static electricity larger than the desired static electricity resistance of the electrostatic protection film 5 due to the charging of the screen mesh at the time. Can do.

  The present invention can be applied not only to the electrostatic protection component having the structure as shown in FIG. 1 but also to various electrostatic protection components having an electrostatic protection film. For example, the electrostatic protection having the structure as shown in FIG. It can also be applied to parts. In the electrostatic protection component of FIG. 13, glass films 12a and 12b are interposed between the sides 5a and 5b of the electrostatic protection film and the surface electrodes 2a and 2b, respectively.

  In the above description, the example of the electrostatic protection component in which one electrostatic protection film 5 is formed on one ceramic substrate 1 has been described. However, the present invention is not limited to this. Two or more electrostatic protection components are provided on one ceramic substrate 1. The electrostatic protection component formed with the electrostatic protection film 5 is also within the scope of the present invention.

  The present invention relates to a paste for an electrostatic protection film, an electrostatic protection component, and a manufacturing method thereof, and is useful when applied to an electrostatic protection component for protecting electronic devices such as portable information devices from electrostatic pulses and external noise. is there.

  DESCRIPTION OF SYMBOLS 1 Ceramic substrate, 1a Substrate surface, 1b Substrate back surface, 1c, 1d Substrate end surface, 2, 2a, 2b Front electrode, 2a-1, 2a-2, 2b-1, 2b-2 End of front electrode, 3a, 3b Back electrode, 3a-1, 3b-1 End of back electrode, 4 Gap, 5 Static electricity protection film, 5a, 5b Side part of static electricity protection film, 5c Center part of static electricity protection film, 6a, 6b Upper electrode, 7 Middle Layer, 8 protective film, 8a, 8b protective film end, 9a, 9b end surface electrode, 9a-1, 9a-2, 9b-1, 9b-2 end surface electrode end, 10a, 10b nickel plating film, 11a , 11b Tin plating film, 12a, 12b Glass film

Claims (3)

An electrostatic protection paste for forming an electrostatic protection film of an electrostatic protection component,
It is a mixture of silicone resin, aluminum powder, and zinc oxide powder.
Whereas the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight,
The aluminum powder has an average particle size of 3.0 to 3.6 μm, and the zinc oxide powder is distributed at a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. paste. In an electrostatic protection component having an insulating substrate, a surface electrode formed on the insulating substrate and facing through a gap, and an electrostatic protection film formed in the gap and connected to the surface electrode,
The electrostatic protection film is a mixture of three components of silicone resin, aluminum powder, and zinc oxide powder.
Whereas the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight,
The aluminum powder has an average particle size of 3.0 to 3.6 μm, and the zinc oxide powder is distributed in a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. . A step of forming a surface electrode by applying and patterning an electrode paste on an insulating substrate by a screen printing method;
Firing the surface electrode;
Cutting the fired surface electrode to form a gap, and the surface electrode faces through the gap; and
A step of forming an upper electrode by applying and patterning a conductive paste to each of the opposing front electrodes through the gap by a screen printing method;
By applying a pattern for applying an electrostatic protection paste to the gap by screen printing, an electrostatic protection film is formed in the gap, and the electrostatic protection film is connected to the opposing surface electrode through the gap. Process,
Baking the upper electrode and the electrostatic protection film simultaneously;
In a method of manufacturing an electrostatic protection component having
The electrostatic protection paste is a mixture of three components of silicone resin, aluminum powder, and zinc oxide powder.
Whereas the silicone resin is 100 parts by weight, the aluminum powder is 60 parts by weight or more, 200 parts by weight or less, the zinc oxide powder 6 0 parts by weight or more, or less 1 6 0 part by weight,
The aluminum powder has an average particle size of 3.0 to 3.6 μm, and the zinc oxide powder is distributed in a volume resistivity of 200 MΩcm or more and a particle size of 0.3 to 1.5 μm. Manufacturing method.

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