JPH03217416A - Electronic part sealer - Google Patents

Abstract

PURPOSE:To provide the title sealer low in melt viscosity, high in toughness, excellent in resistance to moisture and heat and durability, composed of an aromatic polyester made up of each specific structural unit at specified proportion. CONSTITUTION:The objective sealer composed of an aromatic polyester made up of structural units of formula I-III [Ar1 are at least two groups of formula VI, V, and IV; Ar2 is at least one group of formula IV, VI, VII, and VIII (X is H or Cl), except that Ar1 are of formula IV and V, and Ar2 is of formula IV], respectively. The amounts of the respective structural units are such as to be as follows: (1) the structural unit of the formula I: 40-95mol% of the formula I + formula II; (2) the structural unit of the formula II: 60-5mol% of the formula II + formula III; (3) the structural unit of the formula III is virtually equimolar to that of the formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronic component encapsulant made of aromatic polyester. More specifically, the present invention relates to an electronic component encapsulant that has low melt viscosity, high toughness, high heat resistance, and excellent moisture resistance.

<Prior art> Electronic components such as ICs, transistors, diodes, capacitors, etc. are made of ceramics, synthetic resins, etc. in order to prevent their characteristics from changing due to the external atmosphere, to prevent deformation due to external forces, and to maintain electrical insulation. The sealing is done by

Conventionally, thermosetting resins such as silicone resins and orthocresol novolak-type epoxy resins have been used as synthetic resin encapsulants, but these thermosetting resins take a long time to thermoset and are difficult to mold. It takes a long time, requires a boss cure, mold stains occur as the number of molding shots increases, and there is a high content of hydrolyzable chlorine caused by the resin raw material Ebicrostohydrin. For example, there were problems such as corrosion and other negative effects on the wiring.

As a method to solve such problems, diols such as p-hydroxybenzoic acid, phenylhydroquinone, and chlorohydroquinone, terephthalic acid, 1.
Japanese Patent Laid-Open No. 6044521 discloses that a liquid crystalline polyester made of a dicarboxylic acid such as 4-cyclohexylene dicarboxylic acid can be used as a sealant for integrated circuit modules.
It is disclosed in the publication No.

Additionally, JP-A-60-40163 discloses the use of polyester and particulate inorganic materials copolymerized with 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, etc. for sealing electronic components. There is.

<Problems to be solved by the invention> However, the polyester disclosed in JP-A No. 60-44521 has low toughness, so it is necessary to increase the degree of polymerization in order to use it for direct sealing of electronic components, such as ICs. As a result, the melt viscosity increases, causing deformation and damage to the wiring material, and glass transition temperature (Tg>150).
℃ or less, and had low heat resistance, and there were problems with solder heat resistance, so it was not sufficient.

Furthermore, the polyester disclosed in JP-A No. 60-40163 has problems with adhesion to electronic parts and has insufficient moisture resistance, so when used as a sealant for electronic parts, it has poor durability. There was a problem with that, but it wasn't good enough.

Therefore, an object of the present invention is to obtain an electronic component encapsulant that has low melt viscosity, high toughness, and excellent heat resistance and moisture resistance.

<Means for Solving the Problems> The present inventors have made extensive studies to solve the above problems, and as a result, have arrived at the present invention.

That is, the present invention consists of the following structural units (1) to (I[I), and the structural unit (I) is [(I>+(■)] 40 to
95 mol%, structural unit (n) is [(n)+(III)]
The present invention provides an electronic component encapsulant comprising an aromatic polyester in which the structural unit (III) is substantially equimolar to the structural unit (II>).

+O-Ar ○→ ...(n) +oc Arz co+ ...(1) represents one or more groups selected from the following, and Ar represents a hydrogen atom or a chlorine atom. ) The above structural unit (E) is a structural unit of polyester produced from p-hydroxybenzoic acid.

In addition, the structural unit (n) is a structural unit formed from two or more aromatic dihydroxy compounds selected from hydroquinone, 4.4-dihydroxybiphenyl, and 2.6-dihydroxynaphthalene, and the structural unit (II [) is terephthalic acid, 2.6-naphthalene dihydrosulfonic acid, 4
．． 4-diphenyl ether dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4-dicarboxylic acid,
1,2-bis(2-chlorophenoxy)ethane-4.4
- Structural units produced from one or more aromatic dicarboxylic acids selected from dicarboxylic acids are shown.

Among these, those having a structural unit produced from 4.4-dihydroxybiphenyl and 2.6-dihydroxynaphthalene as the structural unit (II>) and a structural unit produced from terephthalic acid as the structural unit (In) are particularly preferred.

The above structural unit (I> is [(I>+(If)] of 40 to 9
It is 5 mol%, preferably 60 to 90 mol%. In addition, the above structural unit (II) is [(■) + (II)] 60 to 5
It is mol%, and 40 to 10 mol% is preferable. When the structural unit (I> is more than 95 mol% or less than 40 mol% of [(E〉+(n)]), the resulting polymer has a high melt viscosity and cannot be used as a sealant for electronic components. There is no suitable answer.

Moreover, the structural unit (n) is a structural unit produced from two or more aromatic dihydroxy compounds selected from three types: hydroquinone, 4,4-dihydroxybiphenyl, and 2,6 dihydroxynaphthalene. Structural unit (II>
In the case where the structural unit is formed from a single compound, the melt viscosity becomes high, which is not suitable for the purpose of the present invention. Also, 3 above
Among the aromatic dihydroxy compounds of the species, it is preferable that the structural unit produced from a certain type of compound does not account for more than 80 mol% of the entire structural unit (n), and it is preferable that it does not account for more than 75 mol%. preferable.

Furthermore, the structural unit (I) and the structural unit (II>) are substantially equimolar.

In addition, when polycondensing the aromatic polyester used in the electronic component encapsulant of the present invention, the above structural units (I) to (I)
In addition to the constituent components, isophthalic acid, 4,4-diphenyldicarboxylic acid, 3.3-diphenyldicarboxylic acid, 3,4-diphenyldicarboxylic acid, 2.2-diphenyldicarboxylic acid, etc. aromatic dicarboxylic acids, alicyclic dicarboxylic acids such as hexahydrophthalic acid, aliphatic dicarboxylic acids such as adivic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2,2-bis(4-hydroxyphenyl)propane , bis(4-hydroxyphenyl)
Aromatic dihydroxy compounds such as sulfone, aliphatic and cycloaliphatic diols such as 14-butanediol, 1,6-hexanediol, neopentyl glycol, ethylene glycol, diethylene glycol, polyethylene glycol, and 1,4-cyclohexanedimethanol. , m-hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, p-aminobenzoic acid, p-aminophenol, etc., in small proportions that do not impair the purpose of the present invention. Can be polymerized.

The aromatic polyester used in the electronic component encapsulant of the present invention can be produced according to the conventional polyester polycondensation method, and there are no particular restrictions on the production method, but typical production methods include p-hydroxybenzoic acid, for example. , a method in which a phenolic hydroxyl group is acetylated from an aromatic dihydroxy compound such as 4,4-dihydroxybiphenyl, an aromatic dicarboxylic acid such as terephthalic acid, and acetic anhydride, followed by a deacetic acid polycondensation reaction. However, the structural unit (n
), it is preferable to use 2,6-diacetoxynaphthalene instead of 2,6-dihydroxynaphthalene.

Polymerization catalysts can be used for these polycondensation reactions, but when used as a sealant for electronic components, it is important to avoid the presence of ionic substances such as Na+ and K+ in the system, which may accelerate corrosion of All-I wiring. It is preferable not to use a catalyst containing Na, K, etc.

The aromatic polyester used in the electronic component encapsulant of the present invention has thermotropic liquid crystallinity that exhibits optical anisotropy in a molten state.

Further, the melt viscosity of the aromatic polyester used in the electronic component encapsulant of the present invention is preferably 10 to 5,000 poise,
In particular, 10 to 3,000 voids is preferred.

Note that this melt viscosity is a value measured using a Koka type flow tester at a temperature of (liquid crystal start temperature + 40°C) and a shear rate of 200 (1/sec).

The electronic component encapsulant of the present invention has a low melt viscosity, can be injection molded at low pressure, and can be used for encapsulating ICs, transistors, diodes, capacitors, and the like.

Note that an inorganic filler can be added to the electronic component encapsulant of the present invention, and it is preferable to add an inorganic filler. Specific examples of fillers include glass fibers, glass beads, metal oxides such as silicon oxide and aluminum oxide, and metal nitrides such as silicon nitride and boron nitride.
Among these, fused silica and crystalline silica are preferred, and fused silica is particularly preferred. Regarding particularly preferred fused silica,
Crushed silica, spherical silica, and other shapes can be used, and spherical silica is more preferably used from the viewpoint of fluidity. Further, as for the granular or spherical inorganic filler, it is preferable that the average particle diameter thereof is 70 μm or less.

The amount of these inorganic fillers added is 2
0 to 80% by weight is preferred.

Moreover, these inorganic fillers can also be used by treating their surfaces with a known surface treatment agent. Examples of surface treatment agents include silane compounds, titanate compounds,
Examples include epoxy compounds.

Furthermore, additives such as nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and flame retardants, and other thermoplastic resins are added to the electronic component encapsulant of the present invention, It is also possible to impart desired properties to molded articles.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 p-human xybenzoic acid 884 g (6.4 mol), 4
．． 1-dihydroxybiphenyl 179g (0.96 mol), 2.6-diacetoxynaphthalene 156g (0
．． 64 mol), terephthalic acid 266g (1.6 mol)
and 934 g (9.15 mol) of acetic anhydride in a stirrer,
The mixture was charged into a reaction vessel equipped with a distillation tube, and acetic acid depolymerization was performed under the following conditions.

First, under a nitrogen gas atmosphere at 100 to 250°C for 5 hours,
After reacting at 50 to 340°C for 2 hours, 340°C, 1.
The pressure was reduced to 1 mmH () in 5 hours, and the reaction was further carried out for 1 hour to complete the polycondensation, whereupon a nearly theoretical amount of acetic acid was distilled out, and a resin having the following theoretical structural formula was obtained.

k/j/m/n=80/1 2/8/20 Also, this polyester was placed on the sample stage of a polarizing microscope and the optical anisotropy was confirmed by raising the temperature.The result was 287°C, which was good. It showed excellent optical anisotropy. Further, the melt viscosity measured at 327° C. was 520 voids (shear rate 200 (1/sec)).

60% by weight of this resin and 40% by weight of fused silica (spherical particles with an average particle size of 20 μm) were extruded into pellets at 320° C. using an extruder.

This composition was applied to an injection molding machine exclusively for inserts, and a semiconductor element was encapsulated. The semiconductor element used was one in which a semiconductor chip was placed on each of ten support frames, and electrodes of the semiconductor chips and terminals of the support frame were connected with aluminum wiring. The molding pressure was selected to be the lowest pressure that would completely fill the mold with resin.

The obtained sealing sample was subjected to a moisture resistance test at 121°C under 2 atmospheres of water vapor pressure for 100 hours, and the leakage current values were measured for 10 sealing parts, and the average was 10-
It was 3μA.

In addition, the heat cycle test of the above sealed sample was conducted at -55
℃, +155℃, 30 minutes each, 1,000 cycles, crack occurrence rate was 2%, defective (wire breakage) incidence was 3.
%Met.

Example 2 In a reaction vessel similar to Example 1, 829 g (6.0 mol) of p-hydroxybenzoic acid, 249 g (1.34 mol) of 4.4-monodihydroxybiphenyl, and 72.7 g (0.66 mol) of hydroquinone were added. ), 432 g (2.0 mol) of naphthalene dicarboxylic acid and 1123 g of acetic anhydride
(11.0 mol) was charged, and acetic acid depolymerization was performed under the same conditions as in Example 1. As a result, a resin having the following theoretical structural formula was obtained.

k/j/m/n=75/1 6.7/8.3/25 Furthermore, the liquid crystal initiation temperature of the obtained bolimar was 300°C, and the melt viscosity measured at 340°C was 310 poise (shear rate 200°C). (1/sec>).

This polymer was blended with fused silica in the same composition ratio as in Example 1 to form a composition.

When this polymer was used as a sealant in the same manner as in Example 1 and a moisture resistance test was conducted under the same conditions, the leakage current value was 10.
It was found to be as low as -3 μA.

Further, as a result of heat cycling, good results were obtained with a crack occurrence rate of 2% and a defective rate of 4%.

Comparative Example 1 p-hydroxybenzoin #829g (6 mol), 2.6-
488 g (2 moles) of diacetoxynaphthalene, 1332 g (2 moles) of terephthalene and 674 g (2 moles) of acetic anhydride.
(6.6 mol) was reacted in the same manner as in Example 1 to obtain a resin having the following theoretical structural formula.

k/. l! /m=75/25/25 The liquid crystal initiation temperature of the obtained Bolima was 285°C, and the melt viscosity was as high as 2.400 poise when measured at 325°C and a shear rate of 200 (1/sec). .

This volima was blended with fused silica in the same composition ratio as in Example 1 to form a composition.

This composition was used in a molding machine exclusively for inserts in the same manner as in Example 1, and a semiconductor element was molded into a sealed mold. When the obtained sample was subjected to a moisture resistance test under the conditions of Example 1, the average leakage current value was 102 μA. In addition, the heat cycle test results showed a crack occurrence rate of 9% and a failure (disconnection) occurrence rate of 2.
It was 4%.

<Effects of the Invention> According to the present invention, an electronic component encapsulant having low melt viscosity, high toughness, excellent moisture resistance and durability, and high heat resistance can be obtained.

Claims (1)

[Claims] Consisting of the following structural units (I) to (III), the structural unit (
I) is 40 to 95 mol% of [(I) + (II)], structural unit (II) is 60 to 5 mol% of [(II) + (III)],
An electronic component encapsulant comprising an aromatic polyester in which the structural unit (III) is substantially equimolar to the structural unit (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(III) (Top In the formula, Ar_1 is two or more groups selected from ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, Ar_2 There are ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Indicates one or more groups selected from ▼ Formula,
Except when ▼There are chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and A r_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼. Moreover, X represents a hydrogen atom or a chlorine atom. )