JP3487656B2 - Electronic components for surface mounting - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component for surface mounting having excellent solder heat resistance, and more specifically, an infrared ray for surface mounting which is made of a specific copolyester showing optical anisotropy when melted. It is an electronic component for surface mounting that has little swelling (hereinafter referred to as blister deformation) during reflow or immersion in a solder bath. Furthermore, since the copolyester of the present invention has little contact contamination during use at high temperatures, it is especially for surface mounting. Among electronic components, it is preferably used for relays and switches.

[0002]

2. Description of the Related Art Surface mounting technology is used when an electronic circuit is formed by fixing electronic components such as semiconductors, resistors, capacitors, coils, switches, relays and connectors to a substrate such as a printed circuit board. In addition, soldering having a function of fixing and forming a circuit is performed from the surface of a substrate having an electronic component, which is realized by passing it through an infrared reflow furnace or immersing it in a molten solder bath. This surface mounting technology is rapidly increasing in adoption with the recent trend toward higher integration of electronic circuits and labor saving due to automation. Electronic components such as printed circuit boards, semiconductors, connectors, relays, switches, etc. are often made of thermoplastic resin with excellent moldability. Especially for surface mount electronic components, optical characteristics during melting, which has excellent heat resistance as well as moldability, are used. Copolyesters exhibiting anisotropy (liquid crystalline polyesters) have come to be used. However, even if the liquid crystalline polyester is excellent in heat resistance, if the electronic component is passed through an infrared reflow furnace to form a circuit or immersed in a molten high-temperature solder bath, the liquid crystalline polyester of the electronic component There is a problem that the surface swells in the range of 1 mm ² to several tens of cm ² and so-called blister deformation occurs. In addition, switch parts that have contact points or relay parts that consist of closed containers often cause metal contacts to be contaminated by the relatively high-temperature gas generated from liquid crystalline polyester, often causing poor conduction. . In order to avoid this problem, a method of volatilizing the gas by placing the package parts under high temperature conditions after molding has been performed, but due to the demand for labor saving, electronic parts for surface mount relays etc. that do not require high temperature drying are desired. Was there.

[0003]

The inventors of the present invention have found that the liquid crystal polyester is usually essential as a result of diligent research efforts to solve the above problems and provide an electronic component for surface mounting having excellent solder heat resistance. By limiting the amount of p-hydroxybenzoic acid used to a specified amount to a specific amount or less and further using an electronic component made of an aromatic copolyester containing a specific monomer, it is possible to perform infrared reflow treatment during surface mounting or dipping in a solder bath. The inventors have found that they can be used as parts for surface-mounting switches or surface-mounting relays, with little blister deformation and little contact contamination during use at high temperatures, and have completed the present invention. That is, the present invention, as a constituent, the following general formula (1), (2), (3)
, Including the constitutional unit represented by (4), 0 to 10 mol% of the constitutional component of (1), 0 to 80 mol% of the constitutional component of (2), and (3) An electronic component for surface mounting comprising a copolyester having optical anisotropy when melted, wherein the constituent component is 2 to 50 mol% and the constituent component (4) is 2 to 50 mol%. (1) -OC-Ar ₁ -O- (2) -OC-Ar ₂ -O- (3) -OC-Ar ₃ -CO- (4) -O-Ar ₄ -X- (where Ar ₁ is , 1,4-phenylene, and Ar ₂ is 2,
6-naphthalene and phenylene number 2 connected in para position
One or more selected from the above compounds. Ar ₃ is 1,2-phenylene, 1,3-phenylene, 1,
One or more selected from 4-phenylene, 4,4′-biphenylene and 2,6-naphthalene. Ar ₄
1,3-phenylene, 1,4-phenylene, 2,6-phenylene, and one or more kinds selected from the residue of a compound having a phenylene group of 2 or more and having a phenylene group bonded at the para position, or the para position Between phenylene of -O-, -CH _2- , -CO-,
-S-, -SO-, -SO _2- , -CH ₃ CCH _3- , -CF ₃ CCF ₃ -and -O-
(CH ₂₎ is _m -O- _{m = _2~6} 1 kind or 2 or more selected from the combined compound. Also, -X- is -O-
And one or more selected from -NH-. In order to embody the constitutional units (1) to (4), various compounds having ordinary ester forming ability are used. The raw material compounds necessary for forming the copolyester constituting the surface mount electronic component of the present invention will be described in detail below in order.

[0004] The structural unit (1) is a structural unit of polyester produced from p- hydroxybenzoic acid, it is 0 10 mol% blended with respect to all the structural units. Surprisingly, when this amount exceeds 10 mol%, blister deformation becomes remarkable even though it has a proper melting point and sufficient heat distortion temperature, and the metal contact contamination property under high temperature use is high. Becomes worse. Structural unit (2) is 0 to all structural units.
Used at 80 mol%. When this amount exceeds 80 mol%, the melting point rises, and when it is remarkable, an insoluble and infusible substance is formed in the polymer, which makes it difficult to mold the intended electronic component with a normal molding machine. (2) Ar ₂ constituting the component is one or two or more selected from 2,6-naphthalene and a compound having a phenylene number of 2 or more connected in the para position. Structural unit
(3) is used in an amount of 2 to 50 mol% based on all the constituent units.
When this amount is less than 2 mol%, the constituent components of (1) and (2) are in the above range, that is, the constituent unit (1) is 0 to 10 mol% based on all constituent units, and the constituent unit (2) is When the content is 0 to 80 mol% with respect to all the constituent units, the melting point rises, and it becomes difficult to mold the intended electronic component with a normal molding machine. Also this amount
When it exceeds 50 mol%, it is not substantially equivalent to the structural unit (4) and the degree of polymerization remarkably decreases, which is not preferable.
(3) Ar ₃ constituting the component is 1,2-phenylene, 1,3-
Phenylene, 1,4-phenylene, 4,4'-biphenylene,
One or more selected from 2,6-naphthalene. Structural unit (4) is 2 to 50 mol based on all structural units
%used. When this amount is less than 2 mol%, the constituent components of (1) and (2) are in the above range, that is, the constituent unit (1) is 0 to 10 mol% based on all constituent units, and the constituent unit (2) is When the content is 0 to 80 mol% with respect to all the constituent units, the melting point rises, and it becomes difficult to mold the intended electronic component with a normal molding machine. On the other hand, if this amount exceeds 50 mol%, the amount is not substantially the same as that of the structural unit (3) and the degree of polymerization remarkably decreases, which is not preferable. (4) Ar ₄ constituting the component is 1,3-phenylene, 1,4-phenylene, 2,6-phenylene, and a residue of a compound having a phenylene number of 2 or more in which a phenylene group is bonded at the para position (for example, 4 , 4'-biphenylene), or one or more kinds selected from (4'-biphenylene), or -O between para-phenylenes.
-(For example 4,4'-dihydroxydiphenyl ether),
-CH ₂ - (e.g. 4,4'-dihydroxydiphenyl methane), - CO- (such as 4,4'-dihydroxydiphenyl ketone), - S- (such as 4,4'-dihydroxydiphenyl sulfide), - SO ₂ - ( For example, 4,4′-dihydroxydiphenyl sulfone), —CH ₃ CCH ₃ — (eg 4,4′-isopropylidenediphenol), —CF ₃ CCF ₃ — (eg 4,4′-hexafluoroisopropylidenediphenol) And -O- (CH ₂ ) _m-
One or more selected from compounds bound by O- {m = 2 to 6} (for example, 4,4 '-(ethylenedioxy) diphenol). Also, -X- is -O- and
One or more selected from -NH-. The molar ratio of each of the structural unit (3) and the structural unit (4) must be substantially equal as described above, but the degree of polymerization of the copolyester can be controlled by intentionally changing the amount slightly. You can also do it.

As described above, the present invention is a structural unit
By limiting the amount of (1) to 0 to 10 mol%, the blister deformation during surface mounting is suppressed, but within this range industrially easily available component (2),
By limiting the proportions of (3) and (4), melt processability,
It was possible to provide a copolyester having excellent heat resistance and mechanical properties and a composition thereof. Even if the constituent component (2) is 80 mol% or less, the constituent component (3) and
If each of (4) is less than 2 mol%, the melting point remarkably rises and the processing characteristics become very poor.

The copolyester of the present invention is polymerized by a direct polymerization method or a transesterification method, and in the polymerization, a solvent polymerization method, a melt polymerization method, a slurry polymerization method or the like is usually used. In these polymerizations, various catalysts can be used, and typical ones are dialkyl tin oxide, diaryl tin oxide, titanium dioxide, alkoxy titanium silicates, titanium alcoholates, carboxylic acid alkali and alkali. Examples thereof include earth metal salts and Lewis acid salts such as BF ₃ . The amount of catalyst used is generally preferably about 0.001 to 1% by weight, based on the total weight of the monomers.
The polymers produced by these polymerization methods can be further increased in molecular weight by solid phase polymerization in which the polymer is further heated under reduced pressure or in an inert gas.

A liquid crystalline polymer exhibiting optical anisotropy when melted is an essential element in the present invention for having both thermal stability and easy processability. The fused anisotropic property can be confirmed by a conventional polarization inspection method using a crossed polarizer. More specifically, the melt anisotropy is confirmed by using a polarizing microscope manufactured by Olympus, melting the sample placed on the hot stage manufactured by Rincom, and observing it under a nitrogen atmosphere at a magnification of 150 times. it can. The polymer is optically anisotropic and transmits light when inserted between crossed polarizers. If the sample is optically anisotropic, polarized light will be transmitted even if it is in a stationary state, for example.
Liquid crystallinity and melting point (liquid crystallinity manifesting temperature) are considered as indices of the processability of the present invention. Whether or not it exhibits liquid crystallinity is deeply related to the fluidity at the time of melting, and it is essential that the polyester of the present invention exhibits liquid crystalline property in the molten state. Since nematic liquid crystalline polymers cause a significant decrease in viscosity above the melting point,
Generally, the liquid crystallinity at the melting point or higher is an index of processability. The melting point (liquid crystal transition temperature) is preferably as high as possible from the viewpoint of heat resistance, but in consideration of thermal deterioration during polymer melt processing and the processing capacity of the molding machine, it is desirable that it be 350 ° C or less. Becomes
Further, it is preferable that the melt viscosity of the resin is 1 × 10 ⁵ poise or less at a shear rate of 1000 sec ⁻¹ at a temperature equal to or higher than the temperature obtained by adding 10 ° C. to the melting point. More preferably, it is 1 × 10 ⁴ poise or less. These melt viscosities are generally realized by having liquid crystallinity.

Further, in the present invention, it is desirable to add various fibrous, powdery or plate-like inorganic and organic fillers to the above-mentioned copolyester according to the purpose of use. The compounding of the filler shows an excellent effect in reducing the anisotropy of the liquid crystalline polyester, improving the mechanical properties, the heat resistance, etc., but in the conventional liquid crystalline polyester, the blister deformation is rather caused by the compounding of the filler. It was getting worse. The above-mentioned copolyester of the present invention, which has solved this problem, allows the blending of a filler to improve various physical properties without blister deformation, and exhibits a remarkable effect when the filler is blended. As the fibrous filler, glass fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel fiber, aluminum, titanium, Inorganic fibrous substances such as copper and brass and metallic fibrous substances can be mentioned. A particularly representative fibrous filler is glass fiber. In addition, high-melting-point organic fibrous substances such as polyamide, fluororesin, polyester resin, and acrylic resin can also be used. On the other hand, as the particulate filler, carbon black, graphite, silica, quartz powder, glass beads,
Milled glass fiber, glass balloon, glass powder,
Calcium silicon, kaolin, talc, clay, diatomaceous earth,
Wollastonite such as silicate, iron oxide, titanium oxide, zinc oxide, antimony trioxide, metal oxide such as alumina, metal carbonate such as calcium carbonate and magnesium carbonate, metal such as calcium sulfate and barium sulfate. And other ferrites, silicon carbide, silicon nitride, boron nitride, various metal powders, and the like. Examples of the plate-shaped filler include mica, glass flakes, various metal foils and the like. Aromatic polyester fiber, liquid crystalline polymer fiber, aromatic polyamide fiber,
It is a heat-resistant and high-strength synthetic fiber such as polyimide fiber. These inorganic and organic fillers can be used alone or in combination of two or more. The combined use of the fibrous filler and the granular or plate-like filler is a preferable combination particularly in terms of mechanical strength, dimensional accuracy and electrical properties. The content of the inorganic filler is 80% by weight or less based on the total amount of the composition, preferably 1 to
60% by weight. When using these fillers,
If desired, it is desirable to use a sizing agent or a surface treatment agent.

Further, to the polyester of the present invention, other thermoplastic resin may be supplementarily added within a range not impairing the intended purpose of the present invention. Examples of thermoplastic resins used in this case include polyolefins such as polyethylene and polypropylene, aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, and aromatic polyesters such as diols, polyacetals (homo or copolymers), and polystyrene. ,PVC,
Examples thereof include polyamide, polycarbonate, ABS, polyphenylene oxide, polyphenylene sulfide, and fluororesin. In addition, these thermoplastic resins are
A mixture of two or more species can be used. In addition, antioxidants (for example, phosphorus compounds such as tridecyl phosphite, or compounds containing hindered phenol such as trade name Irganox 1010) commonly used for thermoplastic polymers, lubricants (for example, stearyl alcohol, polyethylene wax, etc.) Flame retardants (for example, halogen compounds such as brominated bisphenol A, polymers composed of organic phosphorus compounds, antimony compounds such as antimony trioxide, etc.)
The use of additives well known in the art such as can be selected and used according to the purpose.

[0010]

EFFECTS OF THE INVENTION A copolyester comprising a specific constitutional unit obtained in the present invention, such as a printed circuit board,
Electronic parts such as semiconductors, resistors, capacitors, coils, switches, relays and connectors are less likely to be blister-deformed during surface mounting infrared reflow treatment or immersion in a solder bath, and can form good circuit parts. The surface-mounting electronic component using the copolyester of the present invention is particularly suitable for relays and switches because it has less contact contamination when used at high temperatures.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 As shown in Table 1, 1343 g of para-hydroxybenzoic acid, 889 g of terephthalic acid, 589 g of 1,4-dihydroxybenzene,
1822 g of acetic anhydride and 0.05 g of potassium acetate based on the final theoretical polymer yield of 2500 g were charged into a reactor equipped with a stirrer, a nitrogen introducing pipe and a distilling pipe, and the inside of the reactor was replaced with nitrogen, and then a nitrogen stream was supplied. Under this mixture at 140 ℃ 1
Reacted for hours. This was followed by heating to 270 ° C in 2.5 hours. At this time, about 2020 g of acetic acid was distilled. Then another 300 ° C
Up in 2 hours. By that time, more than 95% of the theoretical acetic acid distillate had distilled. Next, after raising the temperature to 350 ° C in 1 hour, the pressure inside the reaction vessel was gradually reduced, and the temperature was increased to 1 hour in 0.5 hour.
The pressure was reduced to less than mmHg, and 35 powder reaction was performed at this pressure.
During this vacuum, a small amount of acetic acid distilled out. Then, after the reaction was completed, nitrogen was introduced, and the content was taken out. The obtained polymer was pale yellowish white, and DSC manufactured by Perkin Elmer Co., Ltd.
The melting point measured by C. was 329.degree. Further, when the polymer was heated and observed under a crossed Nicol on a hot stage manufactured by Rincom under a polarizing microscope manufactured by Olympus, a nematic liquid crystal pattern was exhibited at a melting point or higher. Next, the obtained polymer was mixed and extruded with 30% by weight of glass fiber in an extruder according to a conventional method to prepare a pelletized resin composition. Connector parts were molded from the pellets by injection molding and a general connector mold. After immersing this connector sample in a molten solder bath set at 10 ° C intervals from 250 ° C to 340 ° C for 10 seconds, observe the surface and check the temperature at which blister deformation was confirmed or the temperature at which connector parts were deformed for 10 seconds. The temperature lower by ℃ was used as the solder heat resistance temperature. The parts obtained in this example did not undergo blister deformation and were deformed at 330 ° C., so the solder heat resistance temperature was 320 ° C. Further, the pellets prepared as described above were injection-molded and IC-sealed with a general IC-sealing die to prepare an IC, and the soldering heat resistance temperature was similarly examined. Next, relay parts were prepared from the pellets prepared as described above by injection molding and a general relay mold. For metal contacts, silver-
A palladium alloy was used. This sample was placed in a constant temperature bath at 160 ° C. and the state of contamination of metal contacts was observed. The pollution situation was evaluated by a 5-point scale, and the situation after 3 days, 1 week, and 2 weeks was observed.
There was almost no contamination with points, 4 points and 4 points.

Examples 2 to 6 Copolyesters were synthesized in the same manner as in Example 1 with the raw material monomers shown in Table 1 in the composition ratio, and glass fibers were further added so that the content of the composition was 30% by weight. The components were blended, and connector parts, ICs, and relay parts were prepared and evaluated in the same manner as in Example 1. In the solder heat resistance test, as shown in Table 1, in all cases, deformation occurred at almost the same temperature as the melting point, but no blister deformation occurred. Also, in the contact contamination test,
Both were excellent.

Comparative Examples 1 to 6 Copolyesters were synthesized in the same manner as in Example 1 with the raw material monomers shown in Table 2 in the compositional ratio, and glass fibers were further added so as to be 30% by weight with respect to the composition. The components were blended, and connector parts, ICs, and relay parts were prepared and evaluated in the same manner as in Example 1. As shown in Table 2, in all cases, blister deformation occurred at a temperature considerably lower than the melting point, and contact contamination was inferior. Further, in Comparative Examples 5 and 6, the viscosity was remarkably increased due to the increase in the melting point during the polymerization of the copolyester, and a good polymer was not obtained, which could not be evaluated.

[0014]

[Table 1]

[0015]

[Table 2]

(Note to table) TPA: terephthalic acid NDA: 2,6-naphthalenedicarboxylic acid BBA: 4,4'-biphenyldicarboxylic acid HQ: 1,4-dihydroxybenzene BP: 4,4'-dihydroxybiphenyl PAP: 4-aminophenol HBA: 4-hydroxybenzoic acid HNA: 2-hydroxy 6-naphthoic acid N / A: Melting point is too high to obtain a molded product, which cannot be evaluated.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 63/00-63/91 C08G 69/44

Claims (5)

(57) [Claims] 1. The following general formulas (1) and (2) are used as constituent components.
, (3), including the structural units represented by (4), the composition of (1) is 0 to 10 mol%, the composition of (2) is 0 to 80 mol% with respect to all the structural units. The component of (3) is 2 to 50 mol%,
An electronic component for surface mounting comprising a copolyester which exhibits optical anisotropy when melted, wherein the constituent component of (4) is 2 to 50 mol%. (1) -OC-Ar ₁ -O- (2) -OC-Ar ₂ -O- (3) -OC-Ar ₃ -CO- (4) -O-Ar ₄ -X- (where Ar ₁ is , 1,4-phenylene, and Ar ₂ is 2,
6-naphthalene and phenylene number 2 connected in para position
One or more selected from the above compounds. Ar ₃ is 1,2-phenylene, 1,3-phenylene, 1,
One or more selected from 4-phenylene, 4,4′-biphenylene and 2,6-naphthalene. Ar ₄
1,3-phenylene, 1,4-phenylene, 2,6-phenylene, and one or more kinds selected from the residue of a compound having a phenylene group of 2 or more and having a phenylene group bonded at the para position, or the para position Between phenylene of -O-, -CH _2- , -CO-,
-S-, -SO-, -SO _2- , -CH ₃ CCH _3- , -CF ₃ CCF ₃ -and -O-
(CH ₂₎ is _m -O- _{m = _2~6} 1 kind or 2 or more selected from the combined compound. Also, -X- is -O-
And one or more selected from -NH-. ) 2. In the constituent component (2), Ar ₂ is 2,6-
Surface mount electronic component according to claim 1 Symbol placement is naphthalene. 3. The copolymerized polyester according to claim 1 or 2.
80 % by weight or less of inorganic filler (based on the total amount of the composition)
Electronic component for surface mounting comprising the polyester resin composition . 4. The surface mounting electronic component is a relay electronic component.
The electronic component for surface mounting according to any one of claims 1 to 3 . 5. The surface mounting electronic component is an electronic part for a switch.
The electronic component for surface mounting according to any one of claims 1 to 3, which is a product .