JP4462872B2 - Wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wiring board used in electronic devices such as various AV devices, home appliances, communication devices, computer devices and peripheral devices.

  Conventionally, a wiring board used for a hybrid integrated circuit in which a predetermined electronic circuit is configured by mounting a large number of active elements such as semiconductor elements such as IC and LSI and passive elements such as capacitive elements and resistance elements is usually made of glass. A copper foil is bonded to the top and bottom surfaces of an insulating substrate made by impregnating an epoxy resin into a cloth, and this is processed into a wiring conductor in the form of a wiring pattern by a subtractive method. A base is manufactured by forming a hole (through hole) and forming a through conductor formed by depositing a conductor layer by plating within the through hole, and an insulating layer called a solder resist is laminated on the main surface. It is manufactured by. Alternatively, in order to further increase the wiring density, an insulating layer made of an epoxy resin or the like is laminated on the main surface of the above-mentioned base, and a through hole (via hole) is formed in the insulating layer by irradiating laser light, and then plating is performed. It is manufactured by forming a build-up part by repeating a process of forming a conductor layer in the through hole by the method and forming a wiring conductor on the surface of the insulating layer several times.

  In general, electronic devices are required to be highly reliable in terms of miniaturization, thinning, weight reduction, high performance such as high-speed operation and low power consumption, and connectivity and weather resistance of each connection part. Wiring boards mounted on such electronic devices are also required to have finer and higher density wiring conductors, and the through conductors formed on the base also have a diameter of 200 μm or less and the distance between adjacent through conductors. Refinement and narrowing of the distance to 300 μm or less are required. For this reason, in order to form a penetration conductor, the laser processing which can perform fine processing rather than drill processing has come to be used.

  However, an insulating substrate formed by impregnating a glass cloth with an epoxy resin has a limit to miniaturization of the through conductor because it is difficult to drill the glass cloth with a laser beam, and the thickness of the glass cloth is limited. Due to the non-uniformity, it is difficult to form a through conductor having a uniform hole diameter. In addition, since the adhesion between the glass cloth and the epoxy resin is poor, migration of the conductor of the through conductor is likely to occur at the interface between the glass cloth and the epoxy resin. There was also a problem that the through conductors were short-circuited to cause insulation failure.

In order to solve such problems, it has been studied to use a liquid crystal polymer film as a material for an insulating substrate (see Patent Document 1). The liquid crystal polymer film is composed of linear molecules that are not easily deformed and has a structure in which the molecules are regularly arranged to some extent, so that it has high heat resistance, high elastic modulus, high dimensional stability, and low hygroscopicity. Therefore, it is not necessary to use a reinforcing material such as glass cloth, and the microfabrication property is excellent. Further, it has a low relative dielectric constant and a low dielectric loss even in a high frequency region, and has excellent high frequency characteristics.
JP 2002-261453 A

  However, a conventional insulating substrate has a thickness of about 0.4 mm to 0.8 mm, and when a base is manufactured using an insulating substrate formed of a liquid crystal polymer film having such a thickness, the liquid crystal polymer film is in the thickness direction. Since the coefficient of thermal expansion is large, the dimensional change in the thickness direction of the liquid crystal polymer film becomes large at a high temperature of 200 ° C. or higher, and extreme stress is applied to the through conductor formed in the liquid crystal polymer film, and the through conductor is disconnected. It had the problem that it ended up. In addition, the adhesion between the liquid crystal polymer film and the wiring conductor and the adhesion between the liquid crystal polymer film and the insulating layer are poor, and peeling occurs at high temperature and high humidity, resulting in poor stacking. Was.

  In recent years, higher density has been demanded, and the number of through conductors in the build-up part has increased and the pattern of wiring conductors has become more complex. If a through-conductor is formed or a wiring conductor with a complicated pattern is formed, the dimensional change due to the thermal expansion of the build-up part tends to be greatly different from that of the insulating layer itself, and the number of through-conductors in the build-up part Also, even if the wiring conductor pattern is slightly different between the upper and lower sides of the wiring board, the wiring board is likely to be warped, and as a result, there is a problem that disconnection occurs at the connection portion with the electronic component on the surface of the wiring board. It was.

  In addition, with the increase in speed and functionality of LSIs, there is a tendency that low dielectric constant materials are used on the silicon surface. Although the lowest dielectric constant material is air, there is a problem in circuit retention, so low dielectric constant material candidates tend to be materials containing many bubbles. A low dielectric constant material containing many bubbles has low strength, so the package that mounts a silicon chip using this material minimizes the difference in coefficient of thermal expansion from the silicon chip and does not cause thermal stress in the silicon chip. Must. For this reason, the thermal expansion coefficient of the package substrate is required to be as close as possible to the thermal expansion coefficient of the silicon chip.

  Also, LSIs tend to be large because they process a lot of data at the same time. As LSIs become larger, it is necessary to increase I / O for data input and output. I / O is currently on the order of thousands, but is expected to reach 10,000 in the future. For this reason, wiring boards are required to have finer wiring. In addition, in order to connect fine wiring exceeding several thousand, it is also required to increase the through-hole density by narrowing the interval between through-holes electrically connecting between insulating layers.

  In a multilayer wiring board, an insulating layer is usually formed on an inner circuit board on which an inner layer circuit is formed, a metal layer is formed thereon, a hole penetrating the entire wiring board is formed, and a via reaching the inner layer circuit is formed. A hole is formed to electrically connect the inner layer circuit and the metal foil, and unnecessary portions of the metal foil are removed by etching. With a normal insulating material, the coefficient of thermal expansion is about 16 PPM / ° C. There was a big difference between 3PPM / ° C. of silicon chip. If this difference is large, heating such as reflow is excessive and thermal stress is generated between the silicon chip and the package substrate due to the difference in thermal expansion coefficient, which causes the low dielectric constant layer on the surface of the silicon chip to be destroyed. There was a problem. Further, since a normal insulating base material uses glass cloth as a reinforcing material, there is a problem that it is difficult to finely process through holes.

  The present invention has been completed in view of the problems of the prior art, and an object thereof is to provide a wiring board having high-density wiring and excellent connection reliability and lamination reliability.

Wiring board of the present invention, together with a liquid crystal polymer film having a thickness of 10 to 200μm thicker than the adhesive layer with an adhesive layer mainly composed of a thermosetting resin are stacked four or more layers, the top layer and also in the lowest layer is disposed the adhesive layer, a wiring conductor which is electrically connected to each other via a through conductor on both principal surfaces and the substrate ing respectively formed, are laminated on both main surfaces of the base body and it is characterized in that it comprises an insulating layer.

Further, according to the wiring board of the present invention, it is desirable that the total thickness of the adhesive layer is 5 to 30% with respect to the sum of the total thickness of the liquid crystal polymer film and the total thickness of the adhesive layer. .

  Moreover, according to the wiring board of this invention, it is desirable for the thermal expansion coefficient of the planar direction of the said liquid crystal polymer film to be negative in the temperature range of 25-200 degreeC.

  Moreover, according to the wiring board of this invention, it is desirable that an adhesive bond layer has an epoxy resin as a main component.

  Moreover, according to the wiring board of the present invention, it is desirable that the adhesive layer has a PPE resin or a PPO resin as a main component.

  Moreover, according to the wiring board of this invention, it is desirable for an adhesive bond layer to contain 10-70 volume% of inorganic fillers.

Moreover, according to the wiring board of the present invention, it is desirable that the inorganic filler is mainly composed of any one selected from silicon oxide, aluminum oxide, silicon carbide, and aluminum nitride.

Further, according to the wiring board of the present invention, it is desirable thermal expansion coefficient of 25 to 200 ° C. after curing of the adhesive layer is 50 × 10 -6 ^/ ℃ or less.

The method for producing a wiring board of the present invention includes (a) a step of forming a through hole in an insulating film having an adhesive layer on at least one surface of a liquid crystal polymer film, and (b) a step of forming a via in the through hole, And (c) a step of laminating a plurality of insulating films each having a via formed in the steps (a) and ( b ).

A method of manufacturing a wiring board of the present invention, it is desirable to Rikatachi formed by the laser beam through the through hole in the step of (a).

According to the wiring board of the present invention, four or more liquid crystal polymer films having a thickness of 10 to 200 μm thicker than the adhesive layer are laminated via an adhesive layer mainly composed of a thermosetting resin , It is arranged the adhesive layer to the top and bottom layers, and the substrate ing respectively formed wiring conductors which are electrically connected to each other via a through conductor on both main surfaces, on both major surfaces of the base body from that it comprises a laminated insulating layer, the thickness of the liquid crystal polymer film 10 to 200μm and thin to suppress the dimensional change due to thermal expansion in the thickness direction of the liquid crystal polymer film to a certain small value, it is formed on the liquid crystal polymer film The stress applied to the penetrating conductor can be reduced. That is, when a single layer of a liquid crystal polymer film is used, a large stress is applied to the through conductor, whereas a thin liquid crystal polymer of 10 to 200 μm is thin even if the total thickness is the same as that of a single layer of liquid crystal polymer film. Stress can be dispersed by laminating four or more films through an adhesive layer. As a result, it is possible to provide a wiring board with excellent connection reliability in which the through conductor does not break even at high temperatures. Further, a liquid crystal polymer film and the wiring conductor are stacked via an adhesive layer, since the liquid crystal polymer film and the insulating layer are laminated through an adhesive layer can be bonded firmly. As a result, no peeling and wiring conductors and liquid crystal polymer film at high temperature and high humidity, can be a wiring substrate and a liquid crystal polymer film and the insulating layer is excellent in not laminated reliability be peeled.

In addition, according to the wiring board of the present invention, the adhesive layer is brittle with respect to bending by increasing the thickness of the liquid crystal polymer film that is more flexible than the adhesive layer that is difficult to bend in the above configuration but is brittle and fragile. Furthermore, the presence of adhesive layers that are difficult to bend above and below the liquid crystal polymer film improves the bending strength of the substrate. As a result, even if stress is generated due to the difference in dimensional change due to thermal expansion of the insulating layers of the build-up part located above and below the wiring board, the wiring board warps and the connection part of the electronic component on the surface of the wiring board It is possible to prevent disconnection.

Further, according to the wiring board of the present invention, it is desirable that the total thickness of the adhesive layer is 5 to 30% with respect to the sum of the total thickness of the liquid crystal polymer film and the total thickness of the adhesive layer. .

  Moreover, according to the wiring board of this invention, it is desirable for the thermal expansion coefficient of the planar direction of the said liquid crystal polymer film to be negative in the temperature range of 25-200 degreeC. Thus, by making the thermal expansion coefficient in the planar direction of the liquid crystal polymer film negative in the temperature range of 25 to 100 ° C., the thermal expansion coefficient of the entire wiring board can be greatly reduced, and the semiconductor having a low thermal expansion coefficient Connection reliability with electrical elements such as elements can be greatly improved.

  Moreover, according to the wiring board of this invention, it is desirable that an adhesive bond layer has an epoxy resin as a main component. By using an epoxy resin as the adhesive layer, it is possible to provide a wiring board with high reliability and high positional accuracy even when a thermal cycle is applied.

  Moreover, according to the wiring board of the present invention, it is desirable that the adhesive layer has a PPE resin or a PPO resin as a main component. These thermosetting resins are desirable because of their excellent heat resistance and electrical characteristics.

  Moreover, according to the wiring board of this invention, it is desirable for an adhesive bond layer to contain 10-70 volume% of inorganic fillers. Thus, especially the quantity of an inorganic filler is added to an adhesive bond layer by 10 volume% or more, The intensity | strength of an adhesive bond layer can be improved or moisture resistance can be improved. Moreover, the adhesive force of an adhesive bond layer is securable by setting it as 70 volume or less.

  Moreover, according to the wiring board of the present invention, it is desirable that the inorganic filler is mainly composed of any one selected from silicon oxide, aluminum oxide, silicon carbide, and aluminum nitride. Of these, silicon oxide and aluminum oxide are desirable because they are readily available and relatively inexpensive, and silicon carbide and aluminum nitride are desirable because of their high thermal conductivity.

Moreover, according to the wiring board of this invention, it is desirable that the thermal expansion coefficient of 25-200 degreeC after hardening of an adhesive bond layer is 50x10 < ^-6 > / degrees C or less. In this way, by controlling the thermal expansion coefficient of the adhesive layer within the above range, the thermal expansion coefficient of the entire wiring board can be reduced, and when an electrical element such as a semiconductor element having a low thermal expansion coefficient is mounted. High connection reliability can be realized.

The method for producing a wiring board of the present invention includes (a) a step of forming a through hole in an insulating film having an adhesive layer on at least one surface of a liquid crystal polymer film, and (b) a step of forming a via in the through hole, And (c) a step of laminating a plurality of insulating films each having a via formed in the steps (a) and ( b ).

  With such a manufacturing method, the wiring board of the present invention can be easily manufactured.

A method of manufacturing a wiring board of the present invention, it is desirable to Rikatachi formed by the laser beam through the through hole in the step of (a). By producing a through-hole with laser light, a fine through-hole can be produced with good reproducibility. Moreover, since there are few consumables compared with the case where a drill is used, cost becomes cheap.

  Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board according to the present invention. In the figure, reference numeral 5 denotes a base, and 6 denotes an insulating layer, which mainly constitute the wiring board 7 of the present invention.

  Note that the wiring board 7 in the present embodiment has two insulating layers 6 on the upper and lower main surfaces of the base 5, wiring conductors 8 formed between the surface and the interlayer, and wiring conductors 8 formed above and below the insulating layer 6. A build-up portion composed of through conductors 9 that electrically connect each other or the wiring conductor 4 and the wiring conductor 8 is formed, and this configuration will be described below.

Substrate 5, together with a liquid crystal polymer film of a thick 10 to 200μm in thickness than the adhesive layer with an adhesive layer mainly composed of a thermosetting resin are stacked four or more layers, the top and bottom layers the adhesive layer is also disposed, the wiring conductor which is electrically connected to each other via a through conductor on both main surfaces and is formed respectively. In the wiring board 7 in FIG. 1, although the ones that are laminated a liquid crystal polymer film 1 a three-layer, liquid crystal polymer film 1 is necessary Tei Rukoto are stacked four or more layers.

  The wiring board 7 of the present invention includes a base 5 and an insulating layer 6 laminated on the main surface of the base 5. With this configuration, the liquid crystal polymer film 1 is made as thin as 10 to 200 μm, so that the dimensional change due to thermal expansion in the thickness direction of the liquid crystal polymer film 1 is suppressed to a certain small value, and the through conductor 3 formed in the liquid crystal polymer film 1 The applied stress can be reduced. That is, when a single layer of the liquid crystal polymer film 1 is used, a large stress is applied to the through conductor 3, whereas the thin liquid crystal polymer film 1 having the same total thickness as the single layer of the liquid crystal polymer film 1 is formed. Stress can be dispersed by laminating a plurality of layers through the adhesive layer 2. As a result, it is possible to obtain the wiring substrate 7 having excellent connection reliability without causing the through conductor 3 to be disconnected even at high temperatures.

Further, a liquid crystal polymer film 1 and the wiring conductor 4 are laminated via an adhesive layer 2, since the liquid crystal polymer film 1 and the insulating layer 6 are laminated via the adhesive layer 2, firmly both Can be glued. As a result, no peeling and the liquid crystal polymer film 1 and the wiring conductor 4 even at high temperature and high humidity, as the wiring board 7 where the liquid crystal polymer film 1 and the insulating layer 6 is excellent in not laminated reliability be peeled You can also.

  Here, the liquid crystal polymer refers to a polymer exhibiting liquid crystallinity or an optically birefringent polymer in a molten state or a solution state, and generally a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state or a liquid crystal property when melted. Including thermotropic liquid crystal polymers exhibiting the following, or liquid crystal polymers of type 1, type 2 and type 3 classified by heat distortion temperature, and the liquid crystal polymers used in the present invention include reliability in a temperature cycle test, From the viewpoint of solder heat resistance and workability, a material having a melting point of 230 to 420 ° C., particularly 270 to 380 ° C. is preferable.

  The thickness of the liquid crystal polymer film 1 is 10 to 200 μm. When it exceeds 200 μm, the dimensional change due to thermal expansion in the thickness direction of the liquid crystal polymer film 1 becomes large, and the stress applied to the through conductor 3 formed in the liquid crystal polymer film 1 tends to increase. Moreover, if it is less than 10 micrometers, the intensity | strength of the wiring board 7 will fall easily.

Moreover, it is desirable that the thermal expansion coefficient in the planar direction of the liquid crystal polymer film 1 is negative in the temperature range of 25 to 200 ° C. In particular, −5 to −10 × 10 ⁻⁶ / ° C. is desirable.

Further, the number of layers of the liquid crystal polymer film 1 constituting the substrate 5 is four layers from the viewpoint that the stress applied to the through conductor 3 due to dimensional change due to thermal expansion in the thickness direction is dispersed as a small stress in a plurality of places instead of one place. That's it .

  In addition, the liquid crystal polymer film 1 is a light stabilizer such as an antioxidant for improving thermal stability and an ultraviolet absorber for improving light resistance, and flame retardancy within a range that does not impair the physical properties of the film. Flame retardants such as halogen or phosphoric acid for the addition of flame retardants, flame retardants such as antimony compounds, zinc borate, barium metaborate, zirconium oxide, higher fatty acids or higher fatty acids for improving lubricity Lubricants such as esters, higher fatty acid metal salts, fluorocarbon surfactants, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide for adjusting thermal expansion coefficient and improving mechanical strength, Calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, titanium titanate Strontium, calcium titanate, aluminum borate, barium stannate, barium zirconate, may contain a filler such as strontium zirconate.

  The particle shape of the filler and the like includes a substantially spherical shape, a needle shape, a flake shape, and the like, and a substantially spherical shape is preferable from the viewpoint of filling properties. The particle diameter is 0.1 to 15 μm and is preferably smaller than the thickness of the liquid crystal polymer film 1.

  The liquid crystal polymer film 1 has a surface buffing, blasting, brushing, plasma treatment, corona treatment, ultraviolet treatment, chemical treatment, etc. in order to improve the adhesion with the adhesive layer 2. It is preferable that the surface treatment be carried out so that the contact angle with water is 3 to 65 ° and the surface energy is 45 to 80 mJ / m 2.

  The wettability of water with respect to the liquid crystal polymer film 1 is correlated with the ratio of active groups capable of hydrogen bonding on the upper and lower surfaces of the liquid crystal polymer film 1, and preferably the upper and lower surfaces of the liquid crystal polymer film 1 are contact angles with water. By setting the angle to 3 to 65 °, the adhesive layer 2 is bonded to the upper and lower surfaces of the liquid crystal polymer film 1 with a strong intermolecular force, and the adhesion between the liquid crystal polymer film 1 and the adhesive layer 2 is further improved. Can be

  If the liquid crystal polymer film 1 has an upper and lower surface where the contact angle with water is smaller than 3 °, the affinity with water becomes extremely strong, and water in the air is easily adsorbed on the liquid crystal polymer film 1, and the liquid crystal A plurality of polymer films 1 and adhesive layers 2 are stacked and water adsorbed when they are laminated by heating and pressing are vaporized, and peeling is likely to occur at the interface between the liquid crystal polymer film 1 and the adhesive layer 2. On the other hand, when the angle exceeds 65 °, the adhesion between the liquid crystal polymer film 1 and the adhesive layer 2 is lowered, and it becomes easy to peel between the two.

  The water used for evaluating the contact angle is water purified by the distillation method or ion exchange method specified in JIS K 0050 “General Rules for Chemical Analysis”, or a combination of reverse osmosis method, detention method, ion exchange method, etc. It is recommended to use water purified by the above method.

In addition, the liquid crystal polymer film 1 has a surface layer that is activated and relatively easy to thermally move, and the adhesive layer 2 is entangled and bonded, thereby further enhancing the adhesion between the two. The surface energy is preferably 45 to 80 mJ / m ² .

When the surface energy of the upper and lower surfaces of the liquid crystal polymer film 1 is less than 45 mJ / m ² , the molecular layer on the surface of the liquid crystal polymer film 1 is not sufficiently activated, and it is difficult to entangle and bond with the adhesive layer 2 well. When the surface area exceeds 80 mJ / m ² , the surface of the liquid crystal polymer film 1 is very reactive and reacts with oxygen in the air to form an oxide with low mechanical strength on the surface. As a result, there is a tendency that the adhesion between the liquid crystal polymer film 1 and the adhesive layer 2 is lowered, and it is easy to peel between the two.

  Next, the adhesive layer 2 is made of a thermosetting resin and has a function of an adhesive when depositing and forming a wiring conductor 4 to be described later, and also serves as an adhesive when laminating the liquid crystal polymer films 1 to each other. Fulfill.

  As such thermosetting resins, epoxy resins, cyanate resins, phenol resins, thermosetting polyimide resins, thermosetting polyphenylene ether resins such as allyl-modified polyphenylene ether resins, and bismaleimide triazine resins are cured. Resin is used, especially from the viewpoint of reliability in thermal cycle test and positional accuracy when forming the wiring conductor 4, thermosetting polyphenylene ether resin such as epoxy resin, cyanate resin, allyl-modified polyphenylene ether, or these What mixed is preferable. In particular, from the viewpoint of improving the high-frequency transmission characteristics, the dielectric constant is as low as the liquid crystal polymer film 1 (2.6 to 3.3), and the low dielectric loss (dielectric loss tangent is 10 × 10 −4 to 40 × It is preferable to contain the thermosetting polyphenylene ether and cyanate resin which show 10-4).

  In addition, the thickness of the liquid crystal polymer film 1 is preferably thicker than the adhesive layer 2 from the viewpoint of compensating for the brittleness of the adhesive layer 2 which is difficult to bend but is brittle and easily broken. Further, from the viewpoint of preventing thickness variation when the adhesive layer 2 is formed, the thickness of the adhesive layer 2 is preferably 5 μm or more.

Furthermore, from the viewpoint of preventing the adhesive layer 2 from cracking, the thickness of the adhesive layer 2 is preferably 100 μm or less.

In addition, the thermal expansion coefficient of the adhesive layer 2 after curing may be 50 × 10 ⁻⁶ / ° C. or less in a temperature range of 25 to 200 ° C. in order to reduce the thermal expansion coefficient of the entire wiring board 7. desirable. Moreover, it is desirable that the total thickness of the adhesive layer 2 is 5 to 30% with respect to the sum of the total thickness of the liquid crystal polymer film 1 and the total thickness of the adhesive layer.

  In particular, when an electrical element having a low thermal expansion coefficient and low strength is mounted on the wiring board 7, the thermal expansion coefficient of the wiring board 7 is lowered by setting the total thickness of the adhesive layer 2 within the above range. can do.

  According to the wiring board 7 of the present invention, the adhesive layer 2 is made brittle with respect to bending by increasing the thickness of the liquid crystal polymer film 1 that exhibits flexibility and is more fragile than the adhesive layer 2 that is brittle and easily broken. Further, the bending strength of the substrate 5 is improved by the presence of the adhesive layer 2 that is difficult to bend above and below the liquid crystal polymer film 1. As a result, even if a stress due to a difference in dimensional change due to thermal expansion of the insulating layers 6 in the upper and lower buildup portions of the wiring board 7 occurs, the wiring board 7 warps and the electronic components on the surface of the wiring board 7 are connected. It is possible to prevent disconnection from occurring at the portion.

  Further, the uppermost layer and the lowermost adhesive layer 2 of the substrate 5 are preferably thicker than the other adhesive layers 2. As a result, the bending strength of the substrate 5 is further improved, and stress due to a difference in dimensional change due to thermal expansion between the insulating layer 6 and the liquid crystal polymer film 1 can be reduced.

  The adhesive layer 2 adds a light stabilizer such as a rubber component for adjusting the elastic modulus, an antioxidant for improving thermal stability, an ultraviolet absorber for improving light resistance, and flame retardancy. Flame retardants for halogen or phosphate, flame retardants such as antimony compounds, zinc borate, barium metaborate, zirconium oxide, higher fatty acids, higher fatty acid esters, higher grades for improving lubricity Lubricants such as fatty acid metal salts, fluorocarbon surfactants, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite for adjusting thermal expansion coefficient and improving mechanical strength , Silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate Silane coupling agents and titanates to improve the bondability and mechanical strength of fillers such as aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. A coupling agent such as a system coupling agent may be contained.

  In particular, when the substrate 5 is formed by laminating and pressing the liquid crystal polymer film 1 and the adhesive layer 2, the adhesive layer 2 is controlled from the viewpoint of suppressing the fluidity of the adhesive layer 2 and preventing the thickness variation of the substrate 5. Preferably contains 10% by volume or more of an inorganic insulating powder as a filler. Further, from the viewpoint of preventing peeling at the time of solder reflow at the bonding interface with the liquid crystal polymer film 1 and the bonding interface with the wiring conductor 4, the content of the inorganic insulating powder is preferably 70% by volume or less. Therefore, the adhesive layer 2 preferably contains 10 to 70% by volume of inorganic insulating powder.

  In addition, the shape of said inorganic insulating powder has substantially spherical shape, needle shape, flake shape, etc., and it is preferable from a filling viewpoint that it is a substantially spherical shape with a particle diameter of 0.1-10 micrometers.

  In the wiring board 7 of the present invention, the wiring conductors 4 electrically connected to each other through the through conductors 3 are formed on both main surfaces of the base body 5. The wiring conductor 4 and the through conductor 3 are 2 to 30 μm in thickness and are made of a highly conductive metal such as copper or gold, and an electronic component (not shown) mounted on the wiring board 7 is connected to an external electric circuit (not shown). ) To electrically connect.

  Such a substrate 5 is made of, for example, a paste obtained by adding a thermosetting polyphenylene ether resin, a solvent, a plasticizer, a dispersant, etc. to an inorganic insulating powder such as silicon oxide having a particle size of about 0.1 to 10 μm. Then, after forming into a sheet to be the adhesive layer 2 by a conventionally known sheet forming method such as a doctor blade method, the sheet and a liquid crystal polymer film 1 having a thickness of 10 to 200 μm subjected to surface treatment such as plasma treatment. A plurality of layers are laminated, and further, a metal foil such as a copper foil to be the wiring conductor 4 is laminated on the uppermost layer and the lowermost layer, and these are conditions in which the temperature is 150 to 300 ° C. and the pressure is 0.5 to 10 MPa (megapascal). For 30 minutes to 24 hours for complete curing by hot pressing to produce a substrate with metal foils on both upper and lower main surfaces, and then etching by using a conventionally known photoresist After patterning the metal foil, the wiring conductor 4, the liquid crystal polymer film 1, and the adhesive layer 2 are penetrated by laser processing using a carbon dioxide laser, YAG laser, UV-YAG laser, metal vapor laser, excimer laser, or the like. By forming a through hole to be formed and further forming a conductor layer on the inner surface of the through hole by a plating method, the through conductor 3 for electrically connecting the wiring conductors 4 on the upper and lower main surfaces is formed.

  In order to improve the laser processability of the metal foil, the surface of the metal foil may be roughened or blackened. Further, in order to improve the plating process, after the through hole is formed, the inner surface of the through hole may be purified by a desmear process or an ultrasonic process that removes the resin adhering to the inside of the through hole.

  Further, a resin 10 made of a thermosetting resin or the like is filled inside the through conductor 3. Such a resin 10 is filled in the hollow portion of the through conductor 3 and has a function of protecting the inner surface of the through conductor 3, and includes an epoxy resin, a cyanate resin, a phenol resin, a thermosetting polyimide resin, and a thermosetting polyphenylene ether. Resin, bismaleimide triazine resin or the like is used.

  Furthermore, in the wiring board 7 of the present invention, the insulating layer 6 is laminated on the main surface of the base 5.

The insulating layer 6 may be a conventionally well-known solder resist for protecting the wiring conductor 4, or a build-up portion in which one or more wiring conductors 8 are formed in order to increase the density of the wiring. The insulating layer 6 for forming may be used.

  Such an insulating layer 6 is made of epoxy resin, cyanate resin, phenol resin, thermosetting polyimide resin, thermosetting polyphenylene ether resin, thermosetting resin such as bismaleimide triazine resin, or polyphenylene ether resin, polyimide resin. A thermoplastic resin is used, and in particular, a thermosetting resin such as an epoxy resin is preferably used from the viewpoint of reliability and positional accuracy in a thermal cycle test.

  Furthermore, the insulating layer 6 is added with a rubber component for adjusting the elastic modulus, an antioxidant for improving thermal stability, a light stabilizer such as an ultraviolet absorber for improving light resistance, and a flame retardancy. Flame retardants such as halogen or phosphoric acid, antimony compounds, zinc borates, barium metaborate, zirconium oxide and other flame retardants, higher fatty acids, higher fatty acid esters to improve lubricity, Higher fatty acid metal salts, lubricants such as fluorocarbon surfactants, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide for adjusting the coefficient of thermal expansion and improving mechanical strength, Zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate Silanes to improve the bondability and the mechanical strength of fillers such as aluminum, aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. A coupling agent such as a coupling agent or a titanate coupling agent may be contained.

  When the build-up portion is formed, the conductor layer of the wiring conductor 8 and the through conductor 9 formed on the insulating layer 6 is preferably made of a highly conductive metal such as copper or gold and is mounted on the wiring board 7. It has the function of electrically connecting the electronic component to be electrically connected to the external electric circuit.

Such a conductor layer of the wiring conductor 8 and the through conductor 9 is formed by laminating or coating the insulating layer 6 on the main surface of the substrate 5, and then carbon dioxide gas laser, YAG laser, UV-YAG laser, metal vapor laser, excimer laser. A through-hole penetrating the insulating layer 6 is formed by laser processing using the like, and then formed on the surface of the insulating layer 6 and the inner surface of the through-hole by plating.

  The surface of the base 5, the surface of the insulating layer 6, and the surface of the wiring conductor 8 are buffed to improve the adhesion between the base 5 and the insulating layer 6 and between the insulating layer 6 and the wiring conductor 8. The surface is preferably roughened by a method such as blast polishing, brush polishing, plasma treatment, corona treatment, ultraviolet treatment, chemical treatment or the like.

  Thus, according to the wiring board 7 of the present invention, a semiconductor element or the like is provided on a connection pad formed on a top surface of the wiring board 7 having the above configuration or a part of the wiring conductor 8 via a conductor bump such as solder. The wiring density is increased by electrically connecting these electronic components and forming conductor bumps such as solder on the connection pads formed on the lower surface of the wiring board 7 or on a part of the wiring conductor 8. A hybrid integrated circuit with excellent connection reliability can be manufactured.

  First, spherical fused silica having an average particle size of 0.6 μm is added to a thermosetting polyphenylene ether resin so that the content thereof becomes 40% by volume, and toluene is used as a solvent, and further a catalyst for promoting the curing of the resin. (2,5-Dimethyl-2,5-di (t-butylperoxy) hexane) was added and kneaded for 1 hour to prepare a varnish. Next, this varnish was applied to the upper surface of a PET (polyethylene terephthalate) film by a doctor blade method to form a sheet as the adhesive layer 2.

Then, liquid crystal polymer films 1 of various thicknesses having a melting point of 290 ° C. were prepared, and a voltage of 27 kV, an atmosphere of O ₂ and CF ₄ (gas flow rates of 80 cm ³ / Min), and surface treatment was performed under conditions of 15 minutes per side x 2 times.

  Next, the sheet as the adhesive layer 2 and the liquid crystal polymer film 1 are alternately laminated, and further a copper foil having a thickness of 12 μm is laminated on the uppermost layer and the lowermost sheet, and then the pressure is 200 ° C. Was completely cured under the condition of 3 MPa and the copper foil was adhered.

  Then, the copper foil is etched using a photoresist so as to form a circuit pattern, and this is irradiated with a carbon dioxide gas laser to form through-holes having a diameter of 100 μm and an interval of 200 μm. The substrate 5 was manufactured by depositing a conductor layer (Cu) in the through hole by plating to form the through conductor 3.

  Further, an insulating layer 6 made of an epoxy resin is laminated on the upper and lower main surfaces of the base 5 and thermally cured, and a through hole is formed in the base 5 with a carbon dioxide gas laser so that a part of the wiring conductor 4 on the base 5 is exposed. The conductor layer (Cu) was formed in the wiring conductor 8 (Cu) and the through hole by the electroless plating method and the electrolytic plating method.

  Furthermore, by repeating these steps, the insulating layer 6 forms a two-layer build-up portion, and the wiring board 7 is manufactured.

  Further, as a comparative example, after laminating a 12 μm copper foil on the upper and lower main surfaces of the liquid crystal polymer film 1 having a thickness of 400 μm, the copper foil was adhered under the conditions of a temperature of 300 ° C. and a pressure of 3 MPa, and then the same as above. A circuit pattern and a build-up portion were formed by the above method, and a wiring board 7 without the adhesive layer 2 was manufactured.

  The connection reliability was evaluated by measuring the conduction resistance between the pads of the wiring conductors 4 above and below the wiring board 7 electrically connected through the through conductors 3, and then connecting the wiring board 7 to a solder bath at 260 ° C. In this case, the conduction resistance after repeating the immersion for 30 seconds in 10 minutes was measured, and the change rate of the conduction resistance was calculated and evaluated. Judgment of good or bad connection reliability was made good when the change rate of the conduction resistance was 15% or less, and bad when it exceeded 15%.

In addition, evaluation of lamination reliability, that is, the uppermost or lowermost adhesive layer 2 and the wiring conductor 4 are peeled off, or the uppermost or lowermost adhesive layer 2 and the insulating layer 6 are peeled off. Whether the insulation between the through conductors 3 has deteriorated due to migration due to moisture or the like is evaluated by performing a high temperature bias test with an applied voltage of 5.5 V on a sample at a temperature of 130 ° C. and a relative humidity of 85%. This was done by measuring the insulation resistance after the test. Judgment of the quality of the lamination reliability was judged as good when the insulation resistance was 1.0 × 10 ⁸ Ω or more, and poor when less than 1.0 × 10 ⁸ Ω.

Table 1 shows the results of connection reliability and stacking reliability.

  From Table 1, when the thickness of the liquid crystal polymer film 1 is less than 10 μm (sample 1), the strength of the wiring board 7 is weak, and the wiring board 7 is damaged during the production. Moreover, when the thickness of the liquid crystal polymer film 1 exceeded 200 μm (samples 7 to 10), it was found that the rate of change in conduction resistance exceeded 15% and the connection reliability was poor.

  In contrast, in the wiring board 7 (Samples 2 to 6) of the present invention, the change rate of the conduction resistance was 15% or less, and it was found that the connection reliability was excellent.

  Furthermore, also in the lamination reliability, it was found that the wiring board 7 (samples 2 to 6) of the present invention has high insulation resistance even after the high temperature bias test.

  Various wiring boards 7 were manufactured in the same manner as in Example 1 by changing the thickness of the adhesive layer 2 in various ways. The through conductors 9 formed in the insulating layer 6 have a diameter of 40 μm and an interval of 150 μm on the upper side of the wiring substrate 7, whereas the lower side has a diameter of 100 μm and an interval of 400 μm. The difference between the upper and lower wiring densities was increased to make it easy to warp.

  Further, as a comparative example, after laminating a 12 μm copper foil on the upper and lower main surfaces of the liquid crystal polymer film 1 having a thickness of 400 μm and 800 μm, the copper foil was bonded at a temperature of 300 ° C. and a pressure of 3 MPa. In the same manner as in Example 1, a circuit pattern and a build-up part were formed, and a wiring board 7 without the adhesive layer 2 was manufactured.

  Then, a semiconductor element was mounted on the wiring board 7 via a solder bump, and was electrically connected by putting it in a 260 ° C. reflow furnace.

Table 2 shows the results of observing the appearance and cut section of the sample after putting them into the reflow furnace.

  From Table 2, in the wiring board 7 without the adhesive layer 2 (samples 19 and 20), the wiring board 7 was warped, and a connection failure occurred in the connection portion with the semiconductor element. In addition, it was found that cracks occurred in the adhesive layer 2 when the thickness of the adhesive layer 2 was greater than the thickness of the liquid crystal polymer film 1 (samples 13, 14, 17, and 18).

  On the other hand, in the wiring substrate 7 (samples 11, 12, 15, and 16), the warp does not occur and no connection failure occurs at the connection portion with the semiconductor element, and the adhesive layer 2 is cracked. It did not occur and was found to be excellent.

  The wiring board 7 of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, the substrate 5 is manufactured by laminating the three layers of the liquid crystal polymer film 1, but the substrate 5 may be fabricated by laminating the liquid crystal polymer film 1 of two layers or four layers or more. Moreover, the insulating layer 6 laminated | stacked on the upper and lower surfaces of the wiring board 7 of this invention may be 1 layer, or 3 layers or more.

The thickness of the liquid crystal polymer film 1, the thermal expansion coefficient, the thickness of the adhesive layer 2, the content of the inorganic filler, the type of resin and the number of laminated layers were changed as shown in Table 3, and the same as in Example 1. Various wiring boards 7 were manufactured. And evaluation similar to Example 1, 2 was performed. In addition, a dummy chip was solder mounted on the wiring board 7 to confirm the state of the dummy chip after mounting. The results are shown in Table 3.

  From Table 3, sample No. 1 was obtained by changing the ratio of the thickness of the adhesive layer 2 and the sum of the thickness of the adhesive layer 2 and the thickness of the liquid crystal polymer film 1. 21 to 25, the above-mentioned ratio is in the range of 5 to 30%. In Nos. 22 to 25, good results were obtained in any of the evaluation items, but sample Nos. In which the ratio exceeded 30% were obtained. In No. 21, a slight crack was observed in the dummy chip.

Sample No. 1 in which the coefficient of thermal expansion of the liquid crystal polymer film 1 was changed. In samples 26 to 30, sample Nos. 1 and 2 in which the liquid crystal polymer film 1 showed a negative thermal expansion coefficient. Samples in 26-29, although good results in any of the evaluation items were obtained, the thermal expansion coefficient of the liquid crystal polymer film 1 is 5 × 10 -6 ^/ ℃ No. In No. 30, a slight crack was recognized in the dummy chip.

  Further, sample No. 1 was prepared by adding amorphous spherical silica as an inorganic filler of the adhesive layer 2 and changing the content thereof in the range of 10 to 70% by volume. In 31-34, the thermal expansion coefficient of the adhesive bond layer 2 also changed with the change of the addition amount of an inorganic filler. In these samples, good results were obtained for all the evaluation items.

  Sample Nos. Using various resins as the adhesive layer 2 were used. Also in 35-41, the favorable result was obtained by all the evaluation items.

It is sectional drawing which shows an example of embodiment of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... Liquid crystal polymer film 2 ...... Adhesive layer 3 ...... Through-conductor 4 ...... Wiring conductor 5 ... ... Base 6 ... Insulating layer 7 ... Wiring board

Claims (10)

Together with a liquid crystal polymer film having a thickness of 10 to 200μm thicker than the adhesive layer with an adhesive layer mainly composed of a thermosetting resin are stacked four or more layers, the adhesive also top and bottom layers agent layer is disposed, the wiring conductors are electrically connected to each other via a through conductor on both main surfaces comprises a substrate ing respectively formed, and laminated on both main surfaces of said substrate an insulating layer A wiring board characterized by that. The wiring board according to claim 1, wherein the relative sum of the total thickness of the total thickness and said adhesive layer of said liquid crystal polymer film, the total thickness of the adhesive layer is from 5 to 30%. The circuit board according to claim 1 or 2 planar direction of the thermal expansion coefficient of the liquid crystal polymer film, characterized in that it is a negative in the temperature range of 25 to 200 ° C.. Wiring board according to any one of claims 1 to 3 wherein the adhesive layer is characterized in that the main component an epoxy resin. Wiring board according to any one of claims 1 to 3 wherein the adhesive layer is characterized in that a main component PPE resin or PPO resin. The wiring board according to claim 4 , wherein the adhesive layer contains 10 to 70% by volume of an inorganic filler. The wiring board according to claim 6 , wherein the inorganic filler contains, as a main component, any one selected from silicon oxide, aluminum oxide, silicon carbide, and aluminum nitride. Wiring board according to any one of claims 1 to 7 the thermal expansion coefficient of 25 to 200 ° C. after curing of the adhesive layer is equal to or is 50 × 10 -6 ^/ ℃ or less. Of claims 1 to 8 A method for manufacturing a wiring board according to any one,
(A) forming a through hole in an insulating film having an adhesive layer on at least one side of the liquid crystal polymer film;
(B) forming a via in the through hole;
(C) (a) and (b) A method for manufacturing a wiring substrate in a feature by including a step of a plurality of layers laminated insulating film having a via fabricated in step. A method for manufacturing a wiring board according to claim 9, said through-hole, characterized in that Rikatachi formed by the laser beam in the step of (a).

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