JP2011000816A - Manufacturing method of electric and electronic component sealed with polyester resin of polymerized cyclic polyester oligomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problems: an epoxy type thermosetting resin so far been used for sealing an electric-electronic component is accompanied with bad smell upon thermosetting, and sealing with conventional thermoplastic resin is accompanied with bad fluidizability and thus shapes to be sealed are limited.SOLUTION: In a manufacturing method including the step of sealing an electric-electronic component with a resin, a cyclic polyester oligomer is introduced into a die under fusing the oligomer at its melting point or higher and an electric-electronic component is sealed with a polyester resin obtained by thermo-polymerizing reaction of the cyclic polyester oligomer in the sealing die.

Description

  The present invention is to seal an electric / electronic component with a high molecular weight polyester resin obtained by melting a cyclic polyester oligomer, pouring it into a sealing mold, and causing a thermal polymerization reaction inside the sealing mold. The present invention relates to a method of manufacturing an electrical / electronic component characterized by

Electrical and electronic parts that are widely used in automobiles and electrical appliances must have electrical insulation from the outside in order to achieve their intended purpose. For example, the electric wire is covered with a resin having electrical insulation. In recent years, in applications where it is necessary to pack complicated electrical and electronic parts in a small capacity such as a cellular phone, various methods are employed for electrical insulation. In particular, when a resin or the like serving as an electrical insulator is molded into a component having a complicated shape such as a circuit board, a characteristic capable of following the shape is required.
A method of sealing an electric / electronic component using an epoxy resin-based thermosetting resin has been conventionally performed. Epoxy thermosetting resins are excellent in adhesiveness and excellent in electrical characteristics, cold resistance, wear resistance, and the like. Epoxy thermosetting resins are used for semiconductor sealing, light electrical sealing and multi-purpose sealing, taking advantage of the excellent characteristics as described above, but with amine-based catalysts and acid anhydrides as curing agents. Since it is a two-component mixed type, it takes time for mixing, or it becomes B-stage (semi-gelled state) at a temperature of 60 ° C. or higher, and is thermoset at 120 ° C. or higher for 2 to 3 hours. There is a problem in terms. There is also a problem of generation of off-flavor due to chemical reaction with the curing agent during heat treatment.

Furthermore, in general, epoxy-based thermosetting resins have a large thermosetting shrinkage, so that a large amount of inorganic filler such as silica has been blended. However, this increases the viscosity of the resin, resulting in high-density wiring circuit boards. There is a problem in terms of sealing properties, such as poor resin fluidity when sealing, and bubbles cannot be removed.

There is an example in which a method of sealing using a thermoplastic resin as a sealing material has been studied (see, for example, Patent Document 1). A method using a general thermoplastic resin has a problem of poor fluidity and damages a component to be sealed, and has not been put into practical use. However, Patent Document 1 discloses a mixture of a liquid crystal polymer and a non-liquid crystal polymer that has recently appeared. Describes a method of melting and sealing at a temperature equal to or higher than the melting point of the thermoplastic resin. However, the sealing method described in Patent Document 1 has a sealing temperature of 280 to 290 ° C., which is higher than the melting temperature (around 260 ° C.) of the solder used to form the circuit of the electric / electronic component. A connection failure of the lead-out component occurs, causing a circuit failure, which is a problem. In particular, lead-free solder is being used recently for environmental use, but the use temperature of this lead-free solder is as low as 220 to 230 ° C., and the sealing method disclosed in Patent Document 1 cannot be sealed. Further, this sealing method requires pressurization of about 500 to 1000 kg / cm ² when injecting into the sealing mold, and there is a problem that the electric / electronic parts are damaged by the pressurization.

  In recent years, products in the electronics field such as automobiles, communication, and home appliances have been actively sealed by the hot melt molding method. In particular, it is increasingly used to protect electronic parts and circuits in automobiles. The reason for this is that the hot melt molding method is a simple sealing method, the equipment cost is low, and the equipment design according to the production line is easy.

  Examples of the resin system used in the hot melt molding method include a polyamide system, a polyester system (see, for example, Patent Documents 2 and 3), and a method using a polyolefin system, an elastomer system, and a reactive hot melt system. Although both are solvent-free and environmentally friendly resin systems, for example, polyamide systems mainly using dimer acid bases have problems such as poor gasoline resistance, alcohol resistance, and scratch resistance. Even those that have better gasoline resistance than polyamide-based resins have problems that it is difficult to keep the resin viscosity low so that no pressurization is required at the time of injection, and that the form of sealing is limited.

Japanese Patent Laid-Open No. 5-190698 JP 2004-83918 A Japanese Patent Application Laid-Open No. 2004-276741

The present invention was devised in view of the current state of the prior art, and its purpose is excellent in melt flowability and excellent sealing moldability, such as being able to cope with complicated sealing forms, electrical insulation, An object of the present invention is to provide a method for producing an electrical / electronic component sealed with a thermoplastic resin having excellent quality characteristics such as wear resistance, heat resistance, and chemical resistance.

As a result of intensive studies to solve the above-mentioned problems, the present inventors made a sealing mold in a state in which not a polyester but a cyclic polyester oligomer having a sufficiently low melting point and viscosity were melted at a temperature equal to or higher than the melting point. If injected, it can be injected in a low viscosity state that does not necessarily require pressurization during injection, and as a result, it is possible to inject and seal resin to every corner even in complicated parts form It has been found that it is possible to provide highly reliable electrical / electronic parts, such as being excellent in sealing performance and being able to greatly reduce the risk of damaging electrical / electronic parts. Furthermore, even if polybutylene terephthalate, which is difficult to inject into a sealing mold because of its high viscosity, if converted into polyester by thermal polymerization inside the sealing mold, electrical / electronic parts Has been found to be excellent in quality such as electrical insulation, abrasion resistance, heat resistance, and chemical resistance, and the present invention has been completed.

That is, according to the present invention, the following manufacturing method is provided.
(1) In a method for producing a resin-sealed electrical / electronic component including a step of resin-sealing an electrical / electronic component, the cyclic polyester oligomer is melted at a temperature equal to or higher than the melting point, and injected into a sealing mold. A method for producing a resin-encapsulated electrical / electronic component, wherein the electrical / electronic component is resin-sealed with a polyester resin obtained by thermally polymerizing the cyclic polyester oligomer inside the mold.
(2) The method for producing a resin-encapsulated electrical / electronic component according to (1), wherein the cyclic polyester oligomer is a cyclic polybutylene terephthalate oligomer and the polyester resin is a polybutylene terephthalate resin.
(3) The method for producing a resin-encapsulated electrical / electronic component according to (2), wherein the reduced viscosity (ηsp / c) of the polybutylene terephthalate resin is 1.0 (dl / g) or more.

In the production method of the present invention, since the cyclic polyester oligomer is injected into the sealing mold in a state of being melted at a temperature equal to or higher than the melting point, the sealing material can be injected in a low-viscosity state. Even if it is a simple part form, the resin can be poured into every corner, and the sealing performance is excellent. Furthermore, according to the manufacturing method of the present invention, since it is converted into polyester by thermal polymerization inside the sealing mold, it is usually injected into the sealing mold because of its high viscosity like polybutylene terephthalate. Electrical and electronic parts can be sealed with polyester that is difficult to achieve, and as a result, electrical and electronic parts with excellent quality such as electrical insulation, wear resistance, heat resistance, and chemical resistance can be easily obtained. Obtainable.

Hereinafter, a method for producing the resin-encapsulated electrical / electronic component of the present invention will be described.
In the method for producing a resin-encapsulated electrical / electronic component according to the present invention, the cyclic polyester oligomer is melted at a temperature equal to or higher than the melting point and injected into the sealing mold, and the cyclic polyester oligomer is thermally polymerized inside the sealing mold. The electrical and electronic parts are resin-sealed with a polyester resin obtained by the above-described method. Here, the electric / electronic parts are, for example, automobiles, ships, airplanes, communications, computers, various sensors for home appliances, control units, connectors, harnesses, printed boards and the like.
Since the cyclic polyester oligomer has a low melting point and low viscosity compared to the polyester after conversion, it can be injected even inside the sealing mold and evenly on the surface of the clamped electrical / electronic component. Can be cast. In addition, since it has excellent melt fluidity, it is not necessary to apply pressure at the time of mold injection, so that it is possible to provide a highly reliable resin-encapsulated electric / electronic component that does not damage the electric / electronic component.

The cyclic polyester oligomer used in the present invention includes cyclic poly C _2-6 alkylene terephthalate oligomers such as cyclic polyethylene terephthalate oligomers, cyclic polypropylene terephthalate oligomers, cyclic polybutylene terephthalate oligomers, and cyclic polycyclohexanedimethylene terephthalate oligomers. can do. These may be used alone or as a mixture. In particular, it is preferable to use a cyclic poly C _2-4 alkylene terephthalate oligomer, and among them, it is particularly preferable from the viewpoint of the properties of the resin after the conversion of the cyclic polybutylene terephthalate oligomer.

The method for preparing the cyclic polyester oligomer is, for example, a method in which a bis-hydroxyalkyl-terminated diester described in JP-A-8-225633 or an oligomer thereof is brought into contact with a high-boiling solvent and an esterification catalyst, as described in Japanese Patent No. 3260664. A method for producing a macrocyclic polyester oligomer by putting a linear polyester in an organic solvent in which an organotin catalyst is present, and the linear polyester described in JP-A-2004-507599 is converted into a macrocyclic oligoester by depolymerization. It can be obtained by manufacturing using a conversion method.
Moreover, you may use a commercial item. For example, as the cyclic polyester oligomer, cyclic polybutylene terephthalate oligomer trade name CBT (registered trademark) containing a dimer to a pentamer of Cyclics, Inc. can be used.

Depending on the method for producing the above cyclic polyester oligomer, it is often a mixture of dimer to heptamer, but there is no particular problem as long as a polyester converted to a high molecular weight is obtained by the subsequent thermal polymerization reaction. In the cyclic polyester oligomer used in the present invention, there is no particular limitation as to how many monomers should be used. However, in general, when a polymer of cyclic polyester oligomer is used, the thermal polymerization reaction is lowered, so that the obtained polyester resin tends to have a low molecular weight component. Therefore, the cyclic polyester oligomer used in the present invention is preferably in the range of dimer to pentamer. A hexameric or higher cyclic polyester oligomer is not preferable because the thermal polymerization reaction is lowered and it is difficult to obtain a sufficiently high molecular weight polyester resin.
The cyclic polyester oligomer used in the present invention preferably has a melting point in the range of 100 to 250 ° C, more preferably in the range of 120 to 230 ° C. A melting point within the above range is preferable because there is little risk of melting the solder used for the electric / electronic component.

In order to convert the cyclic polyester oligomer into a polyester resin by thermal polymerization, it is preferable to add a polymerization catalyst to the cyclic polyester oligomer when the cyclic polyester oligomer is melted or in the previous stage. Examples of the polymerization catalyst that can be used include organotin compounds and titanate catalysts described in Japanese Patent No. 3510952, and dialkyltin alkoxides, tin oxacycloalkanes, and spiros compounds as other catalysts.

  Specific examples of organotin compounds include dialkyltin (iv) oxides such as di-n-butyltin (iv) oxide and di-n-octyltin (iv) oxide, di-n-butyltin (iv) di-n- Examples include acyclic and cyclic dialkyltin (iv) dialkoxides such as butoxide, 2,2-di-n-butyl-2-tin-1,3-dioxacycloheptane, and tributyltin ethoxide. . Commercially available products can be used, and examples thereof include ARKEMA trade names FASCAT 4100 (Butylstannoic acid), FASCAT 4101 (Stannane, butylchlorodihydroxy), FASCAT 4102 (Butyltin tris-2-ethylexoste), and the like. It is not limited. In particular, FASCAT 4101 can be preferably used from the viewpoint of processability and polymerizability.

  Examples of titanate ester catalysts include isopropyl titanate, 2-ethylhexyl titanate, and tetrakis titanate (2-ethylhexyl).

The polymerization catalyst is preferably added to the cyclic polyester oligomer in an amount of 0.001 to 2 mol% and dispersed and mixed. Most preferably, it is 0.005-1 mol%. When the amount of the polymerization catalyst is less than 0.001 mol%, the polymerization reaction tends to be insufficient, and the polymerization tends to be required for a long time. When the amount exceeds 2 mol%, the polymerization reaction proceeds too much by heating and the melt viscosity increases. However, it is not preferable because the fluidity tends to be greatly lowered and it may be difficult to inject into the sealing mold. In the case of using Cyclics non-catalyzed CBT (CBT100) as the cyclic polyester oligomer and FASCAT 4101 as the organotin compound of the polymerization catalyst as an example, it is preferably 0.001 to 2 mol%, more preferably 0 to CBT. 0.005 to 1 mol%, particularly preferably 0.1 to 0.9 mol% of FASCAT 4101 can be added and dispersed and mixed for use.

In the present invention, if desired, rubber components, fillers, flame retardants, additives and the like may be blended with the cyclic polyester oligomer within a range not impairing the object of the present invention.

Next, the cyclic polyester oligomer is melted and flowed at a temperature equal to or higher than its melting point and poured into a sealing mold.
For example, in the case of CBT, the melting point is 139 ° C. The set temperature when melt-flowing and injecting into the sealing mold is preferably in the range of 139 ° C. to 230 ° C., more preferably in the temperature range of 200 ° C. to 220 ° C., particularly preferably in the range of 205 ° C. to 205 ° C. The temperature range is 215 ° C. After the cyclic polyester oligomer is melted, it is preferably injected into the mold within 2 minutes. If it exceeds 2 minutes, the polymerization reaction starts to proceed, the viscosity increases, and the fluidity may decrease, which is not preferable. When the set temperature is less than 139 ° C., the molten resin becomes cloudy, the appearance is not good, and the fluidity is inferior. When the set temperature exceeds 230 ° C., the polymerization reaction proceeds excessively, the viscosity increases, the fluidity decreases, and injection is performed. This tends to be difficult and is not preferable.
When injected into the sealing mold, the reduced viscosity of the cyclic polyester oligomer is preferably in the range of 0.01 to 0.1 (dl / g). If the reduced viscosity of the cyclic polyester oligomer exceeds the upper limit, the melt viscosity is excessively increased, which may make it difficult to inject into the sealing mold.

As the sealing mold used in the present invention, a conventionally known sealing mold such as an aluminum mold used in hot melt molding can be used. Aluminum molds can be processed by pressing at extremely low pressure, and the mold strength is not so high, and aluminum molds have advantages such as being able to quickly remove heat after sealing and cool.

Next, after the molten cyclic polyester oligomer is injected into the sealing mold, it is converted into a polyester resin by a thermal polymerization reaction in the sealing mold to complete the sealing.
For example, when the cyclic polyester oligomer is a cyclic polybutylene terephthalate oligomer, it is converted into a polybutylene terephthalate resin by a ring-opening addition polymerization reaction to complete sealing. When a polymerization catalyst is added to the cyclic polybutylene terephthalate oligomer to convert it into a polybutylene terephthalate resin, it is preferably polymerized at a temperature in the range of 200 to 230 ° C, more preferably in the range of 200 to 220 ° C. is there. When the polymerization reaction temperature is less than 200 ° C., it may take a long time to convert to a polyester, and there is a possibility that low molecular weight components and oligomers remain, which is not preferable. The higher the polymerization reaction temperature, the faster the molecular weight increases. Therefore, when the polymerization reaction temperature exceeds 230 ° C., the melt viscosity at the injection port inside the sealing mold is high and the fluidity is inferior. The polymerization time is preferably about 5 to 15 minutes, for example, when polymerization is performed within the above temperature range. When the polymerization time is less than 5 minutes, the increase in the molecular weight does not proceed sufficiently, a sufficient reduced viscosity cannot be obtained, and a low molecular weight component may remain. Remaining low molecular weight components are not preferable because they contaminate the sealing mold and adversely affect the environmental treatment electrical characteristics. Further, when the polymerization time exceeds 15 minutes, the polyester resin may start to deteriorate, which is not preferable. Cyclic polybutylene terephthalate oligomers are converted to polybutylene terephthalate by at least 88%, and a high molecular weight of 30,000 or more in weight average molecular weight and 1.0 (dl / g) or more in reduced viscosity satisfies sealing properties. Desirable for.

As described above, a resin-encapsulated electrical / electronic component using a polyester resin composed of a cyclic polyester oligomer can be easily produced. The resin-encapsulated electrical / electronic component obtained in this way has a low viscosity compared to the polyester after the cyclic polyester oligomer to be injected has been converted into a high molecular weight, so that it is contained in a complicated encapsulating mold. It is easy to inject and does not require pressurization to uniformly cast the surface of the clamped electrical / electronic component, so that the damage of the electrical / electronic component can be greatly reduced during the manufacturing process. A highly sealed electric / electronic component can be provided.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In addition, the evaluation method of various characteristics was measured as follows.

-Reduced viscosity ηSP / C (dl / g)
20 mg of a sample is dissolved in 10 ml of a mixed solvent (phenol / tetrachloroethane = 60/40 weight ratio) and measured at 30 ° C. using an Ostwald viscometer. The sample was measured for each of the sample immediately before the cyclic polyester oligomer was melted and injected into the mold, and the sample after the thermal polymerization reaction was converted to a high molecular weight.

(2) Weight average molecular weight (Mw)
Obtained from GPC analysis. The measurement conditions are as follows.
The weight average molecular weight was evaluated by excluding low molecular weight components of Mw 1000 or less (in terms of PMMA).
The sample was dissolved in 10 mM HFIP / sodium trifluoroacetate, filtered through a 0.2 μm membrane filter, and GPC analysis of the obtained sample solution was performed under the following conditions.
Equipment: TOSOH HLC-8220GPC
Column: TSKgel SuperHM-H × 2 + TSKgel SuperH2000 (TOSOH)
Solvent: HFIP / sodium trifluoroacetate 10 mM
Flow rate: 0.25 ml / min, concentration: 0.05%
Temperature: 40 ° C, Detector: RI

(3) PBT conversion rate (%)
Assuming that the chromatogram area from the peak start to the peak end of the GPC chromatogram (entire peak) is 100 and the weight average molecular weight Mw from the peak start to about 3000 (PMMA conversion) is the high molecular weight PBT part, the area ratio Was determined as the PBT conversion rate (%).

(4) Sealing layer thickness (μm)
It calculated | required with the film thickness measuring device.

(5) Chip resistance (Ω)
The chip resistance value was obtained according to the measurement method of JIS C 5201-1, and it was confirmed whether or not it was conductive.
The electrical / electronic circuit board used was a 65mm x 65mm glass epoxy board size with mounting components consisting of square jumper chip resistors, PM series electrolytic capacitors and pin connectors. Used eutectic solder (63% tin and the lowest melting point 184 ° C.). The conductor width was 125 μm and the conductor-to-conductor width was 125 μm.

(6) Capacitor capacitance (μF)
The capacitance was determined according to the measurement method of JIS C 5201-1.
When measurement was performed with a measuring instrument (digital multimeter) and a capacitance of 100 μF or more was shown, it was determined that there was no problem (upper limit of measurement was 100 μF).
The electrical / electronic circuit board used was a 65mm x 65mm glass epoxy board size with mounting components consisting of square jumper chip resistors, PM series electrolytic capacitors and pin connectors. Used eutectic solder (63% tin and the lowest melting point 184 ° C.). The conductor width was 125 μm and the conductor-to-conductor width was 125 μm.

(7) It was inspected whether the resin was molded according to the filling mold or whether the resin was evenly cast between the conductors of the electric and electronic parts. OK ... Pass, NG ... Defect.

(8) Appearance Visually inspected for defects such as dirt, faintness and foreign matter. No ... no defects, yes ... smears, etc.

Example 1
Weigh 40g of cyclic polybutylene terephthalate oligomer CBT100 in a glass bottle containing 100g and weigh the catalyst FASCAT4101 so that the catalyst concentration is 0.3mol%, and dry dry blend at 80 ° C overnight to reduce the moisture to 500ppm or less. did. This is melted at 210 ° C. × 2 minutes (reduced viscosity ηSP / c = 0.083 (dl / g) at this time) and poured into a sealing mold, polymerized at 200 ° C. × 10 minutes, and reduced viscosity ηSP An electric / electronic circuit board having a sealing layer (2 mm thick) made of polybutylene terephthalate resin having a /c=1.78 (dl / g), a PBT conversion of 96.1%, and a weight average molecular weight of 65,500 was obtained.
The molded state on the circuit board was also good, and it was covered with resin to every corner of the electronic / electrical circuit board, and it was confirmed that the filling and appearance were good. Moreover, when the chip resistance of the obtained sealed circuit board after molding was measured with a multimeter, it was confirmed that it showed a value of 0.3 to 0.4Ω and was conducted without any problem. In addition, the capacitance of the electrolytic capacitor (product number 220 μF) was also confirmed to be good because the upper limit of the multimeter was 100 μF or more.

(Example 2)
A cyclic polybutylene terephthalate oligomer and a polymerization catalyst were prepared in the same manner as in Example 1 except that the catalyst concentration was changed to 0.2 mol%, and then melted at 210 ° C. for 2 minutes (reduced viscosity ηSP / c = 0.080 ( dl / g)), and injected into a sealing mold in the same manner as in Example 1 to conduct polymerization at 200 ° C. × 10 for a reduced viscosity ηSP / c = 1.54 (dl / g), PBT conversion 96.1%, A circuit board having a sealing layer having a weight average molecular weight of 67,100 and a thickness of 2 mm was obtained. The molded state on the circuit board was also good, and it was covered with resin to every corner of the electronic / electrical circuit board, and it was confirmed that the filling and appearance were good. The chip resistance of the obtained sealed circuit board showed a value of 0.3 to 0.4Ω, and it was confirmed that there was no problem with the capacitance.

(Example 3)
Sealing was carried out in the same manner as in Example 2 except that the temperature during mold polymerization was changed to 200 ° C. × 15 minutes, reduced viscosity ηSP / c = 1.56 (dl / g), PBT conversion 96.1% A circuit board having a sealing layer having a weight average molecular weight of 57,600 and a thickness of 2 mm was obtained. The molded state on the circuit board was also good, and it was covered with resin to every corner of the electronic / electrical circuit board, and it was confirmed that the filling and appearance were good. The chip resistance of the obtained sealed circuit board was 0.3 to 0.4Ω, and it was confirmed that there was no problem with the capacitance.

(Comparative Example 1)
PBT 40g obtained from the polycondensation reaction (GT430, reduced viscosity ηSP / c = 1.13 (dl / g) manufactured by Toyobo Co., Ltd. was melted at 250 ° C. for 10 minutes and injected into the sealing mold. Resin clogging occurred at this stage and sealing was stopped.

  The method for producing electrical / electronic parts using the thermoplastic resin comprising the cyclic oligomer of the present invention is applicable to various fields such as circuit sealing of high-density wiring using low melt viscosity and hot melt molding method with less equipment investment. Can be used for applications. Further, the present invention provides a method for producing resin-encapsulated electrical / electronic parts that are environmentally friendly, including no solvent and no reaction odor during polymerization.

Claims (3)

In a method for producing a resin-sealed electrical / electronic component including a step of resin-sealing an electrical / electronic component, the cyclic polyester oligomer is melted at a temperature equal to or higher than the melting point and injected into the sealing die, A method for producing a resin-encapsulated electrical / electronic component, comprising sealing an electrical / electronic component with a polyester resin obtained by subjecting the cyclic polyester oligomer to a thermal polymerization reaction. The method for producing a resin-encapsulated electrical / electronic component according to claim 1, wherein the cyclic polyester oligomer is a cyclic polybutylene terephthalate oligomer, and the polyester resin is a polybutylene terephthalate resin. The method for producing a resin-encapsulated electrical / electronic component according to claim 2, wherein the reduced viscosity (ηsp / c) of the polybutylene terephthalate resin is 1.0 (dl / g) or more.