JPH01104648A - Sealing resin composition - Google Patents

Abstract

PURPOSE:To obtain a sealing resin composition, consisting of a blend prepared by homogeneously dispersing and blending a polyimide obtained by thermally polymerizing bismaleimide in a novolak type phenolic resin, epoxy resin and inorganic filler and having a low stress, excellent moisture and solder heat resistance. CONSTITUTION:A composition containing (A) a resin blend, obtained by melting (A1) 100pts.wt. novolak type phenolic resin while heating at >=120 deg.C, blending (A2) 0.1-100pts.wt. bismaleimide (e.g. N,N'-4,4'-diphenylmethane bismaleimide) and stirring the resultant blend while heating for >=30min to provide the component (A2), thermally polymerized into a polyimide resin in the resin (A1) and homogeneously dispersed and blended therein, (B) an epoxy resin and (C) an inorganic filler as essential components. The composition contains 0.01-30wt.% polyimide resin and 25-90wt.% component (C). The equivalent ratio of epoxy groups in the component (B) to phenolic OH groups in the component (A1) is 0.1-10.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides an electronic and
The present invention relates to a resin composition for sealing electrical parts and the like.

(Prior Art) Conventionally, methods have been used to seal electronic components such as diodes, transistors, and integrated circuits using thermosetting resins. This resin sealing is widely put into practical use because it is economically advantageous compared to hermetic sealing methods using glass, metal, and ceramics.It is one of the thermosetting resins used as sealing resins. Epoxy resins are most commonly used. By the way, epoxy resins are blended with curing agents such as acid anhydrides, aromatic amines, and novolac-type phenolic resins, but among these, epoxy resins that use novolac-type phenolic resins as curing agents do not use other curing agents. It is widely used as a semiconductor encapsulation material because it has superior moldability and moisture resistance, is non-toxic, and is inexpensive compared to other materials.

(Problem to be solved by the invention) However, in recent years, in the field of semiconductor integrated circuits, elements have become more highly integrated and pellets have become larger. However, this method had the disadvantage that it contracts during molding and hardening, applying stress to the semiconductor element, resulting in poor reliability. When a molded product (sealed product) using such a resin is subjected to a hot/cold cycle test, open bonding wires, resin cracks, and pellet cracks occur, making the product unable to function as an electronic component. Furthermore, automation of the process of assembling semiconductor devices is currently being promoted. For example, when attaching a flat package type semiconductor device to a circuit board, conventionally, each lead pin was soldered.
Recently, a method has been adopted in which the entire semiconductor device is immersed in a solder bath heated to 250° C. or higher to perform soldering.

When the entire molded product using conventional epoxy resin is immersed in a solder bath, there is a drawback that peeling occurs between the resin and the semiconductor pellet and frame, resulting in significant deterioration of moisture resistance.

The present invention was made to eliminate these drawbacks, and an object of the present invention is to provide a sealing resin composition that is low in stress and has excellent moisture resistance, soldering heat resistance, and crack resistance.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive research aimed at achieving the above object, the present inventors have developed a three-dimensional structure of an epoxy resin using a novolac type phenolic resin as a curing agent. By introducing a polyimide resin made by thermally polymerizing bismaleimide as a separate network structure that is not mutually involved, a composition with low stress and excellent moisture resistance, soldering heat resistance, and crack resistance can be obtained. This discovery led to the completion of the present invention.

That is, the present invention provides (A) (a) in a novolac type phenolic resin,
(b) Polyimide resin made by thermally polymerizing bismaleimide is uniformly dispersed and mixed! lJf! The mixture contains (B) an epoxy resin and (C) an inorganic filler as essential components, contains 0.01 to 30% by weight of the borimide resin based on the entire resin composition, and contains 25 to 90% by weight of the inorganic filler. % by weight of a sealing resin composition. Then, the resin mixture is made by blending 0.1 to 100 parts by weight of bismaleimide to 100 parts by weight of novolak type phenolic resin, thermally polymerizing the bismaleimide in the novolak type phenol resin to form a polyimide resin, and converting it into a novolak type phenolic resin. It is uniformly dispersed and mixed in phenolic resin, and the equivalent ratio of epoxy group (i) and phenolic hydroxyl group (ii) [(
+)/(ii)] is in the range of 0.1 to 10.

The resin mixture (A) used in the present invention is obtained by uniformly dispersing and mixing (b) a polyimide resin in (a') a novolac type phenol resin.

The (a) novolac type phenolic resin which is a component of the resin mixture includes novolac type phenol resins obtained by reacting phenols such as phenol and alkylphenols with formaldehyde or paraformaldehyde, and modified resins thereof, such as epoxidized or butylated resins. Examples include novolac type phenolic resin, etc.
These may be used alone or in combination of two or more. The blending ratio of novolac type phenolic resin is as described in (B) below.
It is desirable that the equivalent ratio [(i)/(it)] between the epoxy group (i) of the epoxy resin and the phenolic hydroxyl group (it) of the novolak type phenolic resin (a>> phenolic hydroxyl group (it) of the novolac type phenolic resin) is within the range of 0.1 to 10. If this equivalent ratio exceeds 0.1 or 10, the moisture resistance, molding workability, and electrical properties of the cured product will deteriorate, which is undesirable in either case. good.

The polyimide resin (b), which is another component of the resin mixture, is a polyimide resin obtained by thermally polymerizing bismaleimide. This polyimide resin is desirably contained in an amount of 0.01 to 30% by weight based on the entire resin composition. If the proportion is less than 0.01% by weight, low stress and
It has no effect on solder heat resistance, and if it exceeds 30% by weight, moldability deteriorates, making it unsuitable for practical use. Bismaleimide has the following general formula and can be widely used as long as it is obtained by reacting 2 moles of maleic acid with 1 mole of diamine.

[Wherein, R1 is a hydrogen atom or an alkyl group, X is (where R2 is a hydrogen atom, a chlorine atom, or an alkyl group, and T is 10-
1-CH2-1-SO2- or -5-S-11 is 1 to 6
(Represents one number of)] Specific compounds include N,N''-4,4'-diphenylmethane bismaleimide, N,N'-methylenebis(3-chloro-p-7enylene) Bismaleimide, N,
N'-4,4'-diphenylsulfone bismaleimide, N, N'-4,4'-diphenyl ether bismaleimide, N, N'-ethylene-bismaleimide,
Examples include N,N''-hexamethylene bismaleimide, which may be used alone or in combination of two or more.

The resin mixture is usually produced as follows.

After heating and melting the novolac type phenol resin to 120°C or higher using a universal mixer, heating reaction pot, kneader, etc.,
Add bismaleimide and heat and stir for 30 minutes or more.
In a heated and melted novolac type phenolic resin,
Bismaleimide is thermally polymerized to form a polyimide resin, and the polyimide resin is further uniformly dispersed and mixed in the novolac type phenol resin to form a resin mixture. In this case, the bismaleimide is desirably added in an amount of 0.1 to 100 parts by weight based on 100 parts by weight of the novolac type phenol resin.

If it is less than 0.1 part by weight, it will have no effect on low stress or soldering heat resistance.
Moreover, if it exceeds 100 parts by weight, moldability will deteriorate, which is not preferable.

The epoxy resin (B) used in the present invention is not particularly limited in terms of molecular structure and molecular weight as long as it is a compound having at least two epoxy groups in its molecule, and includes a wide range of resins commonly used in sealing materials. can do. Examples include aromatic resins such as bisphenol type, alicyclic resins such as cyclohexane derivatives, and epoxy novolak resins represented by the following general formula.

(In the formula, R' represents a hydrogen atom, a halogen atom, or an alkyl group, R2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) These epoxy resins can be used alone or as a mixture of two or more types. use

Examples of the inorganic filler (C) used in the present invention include silica powder, alumina, antimony dioxide, talc, calcium carbonate, titanium white, clay, mica, red iron, glass fiber, carbon fiber, etc. Among these, silica powder or alumina are preferably used. The blending ratio of the inorganic filler is 25 to 9 with respect to the entire resin composition.
It is desirable to contain 0% by weight, the proportion is 25J
If the amount is less than i%, there will be no effect on moisture resistance, heat resistance, mechanical properties and moldability, and if it exceeds 90% by weight, bulk will increase and moldability will be poor, making it unsuitable for practical use.

The sealing resin composition of the present invention includes a resin mixture, a novolac type phenolic resin, and an inorganic filler as essential components,
If necessary, for example, natural waxes, 1 synthetic waxes,
Mold release agents such as metal salts of straight chain fatty acids, acid amides, ester paraffins, chlorinated paraffins, bromotoluene,
Flame retardants such as hexabromobenzene and antimony trioxide, colorants such as carbon black and red iron oxide, silane coupling agents, various curing accelerators, etc. can also be appropriately added and blended.

A general method for manufacturing the sealing resin composition of the present invention as a molding material is to use a resin mixture in which a polyimide resin obtained by thermally polymerizing bismaleimide is uniformly dispersed in a novolac type phenol resin, an epoxy resin, After thoroughly and uniformly mixing the raw material composition with the inorganic filler and others selected in a predetermined composition ratio using a mixer, etc., the mixture is further mixed using hot rolls, then cooled and solidified, and then ground to an appropriate size. Use as a molding material. The molding material thus obtained can be applied to sealing, covering, insulating, etc. electronic or electrical components.

(Function) By using a resin mixture in which a polyimide resin obtained by thermally polymerizing bismaleimide is uniformly dispersed in a novolac type phenol resin, the three-dimensional structure of the epoxy resin using the novolac type phenol resin as a curing agent is improved. In addition, a three-dimensional structure of the polyimide resin that does not interact with that structure is created, which greatly improves the heat resistance of the resin composition.
Even when immersed in a solder bath, there is little deterioration in heat resistance, and the stress relaxation effect is large.

(Examples) Next, the present invention will be specifically explained by examples, but the present invention is not limited by these examples.
In the following Examples and Comparative Examples, "%" means "% by weight".

Example 1 Novolac type phenolic resin (phenol equivalent weight 107)
12% resin mixture with polyimide resin made by thermally polymerizing 3% equivalent of bismaleimide to 9% equivalent, 18% cresol novolac epoxy resin (phenol equivalent 215)
, fused silica powder 69%, hardening accelerator 0.3%, ester wax 0.3% and silane coupling agent 0.
4% were mixed at room temperature, further kneaded at 90 to 95°C, cooled, and then ground to produce a molding material. The obtained molding material was transfer-injected into a mold heated to 170° C. and cured to obtain a molded product (sealed product). This molded article was tested for properties related to moisture resistance, stress, etc., and the results are shown in Table 1. Low stress and excellent moisture resistance, especially moisture resistance after immersion in solder, were observed, demonstrating the remarkable effects of the present invention.

Example 2 Novolac type phenolic resin (phenol equivalent weight 107)
13% resin mixture with polyimide resin made by thermally polymerizing 5% bismaleimide equivalent to 8% equivalent, cresol novolak epoxy resin (t 215 per epoxy) 17%
, 69% silica powder, 0.3% curing accelerator, 0.3% ester wax, and 0.4 silane coupling agent.
% was mixed, kneaded, and crushed in the same manner as in Example 1 to produce a molding material. Next, a molded article was obtained in the same manner as in Example 1,
The molded product was tested for moisture resistance, stress, etc., and the results are shown in Table 1. Remarkable effects of the present invention were observed.

Comparative example Cresol novolac epoxy resin (epoxy equivalent: 21
5) To 20%, 10% novolac type phenol resin (phenol equivalent: 107), 69% silica powder, 0.3% hardening accelerator, 0.3% ester wax, and 0.4% silane coupling agent were added. A molding material was produced in the same manner as in Example 1. This molding material was used to make a molded article, and the properties of the molded article were tested in the same manner as in Example 1. The results are shown in Table 1.

Table 1 (unit) *1: Number of cracks is 30 x 25 x 5IIn
25x 25x, 3nI on the bottom of the molded product! A copper plate was embedded in the resin, and the resin was placed in a constant temperature bath at -40°C and +20°C for 30 minutes each, and cracks in the resin were investigated after 15 cycles.

N2: Using the sealing resin composition (molding material), an electrical component having two aluminum wirings was transfer-molded at 170°C for 3 minutes, and then cured at 180°C for 8 hours. For 100 sealed electrical components thus obtained, 12
Perform a moisture resistance test in high-pressure steam at 0°C and evaluate the time it takes for 50% wire breakage (defect generation) to occur due to aluminum corrosion.

*3: Using a sealing resin composition (molding material), an electrical component with two aluminum wirings was adhered to a regular 4270 frame, and transfer molded at 170'C for 3 minutes, 5x 10x 1.511+11 A flat barrier type molded article was obtained, and post-curing was performed at 74,180° C. for 8 hours. This molded product was prepared in advance at 40°C, 90%RH, 1
After 00 hours of moisture absorption treatment, it was placed in a solder bath at 250℃ for 10 hours.
Immersed for seconds. Thereafter, a pressure pressure test (PCT) was conducted in saturated steam at 127° C. and 2.5 atm, and disconnection due to aluminum corrosion was evaluated as a failure.

4: A commercially available strain gauge was attached to the island portion of the DIP 16-pin lead frame, and the strain was measured after curing at 180° C. for 8 hours.

[Effects of the Invention] As is clear from the above explanation and Table 1, the sealing resin composition of the present invention has low stress, moisture resistance, soldering heat resistance,
Because it has excellent heat resistance, it does not cause bonding wire ovens, resin cracks, or burnout cracks.
In addition, it has low stress due to shrinkage during curing and exhibits excellent properties even after being immersed in a solder bath at temperatures of 250° C. or higher. By using this material, highly reliable electronic and electrical components can be obtained.

Claims (1)

[Claims] 1. (A) (a) A resin mixture in which bismaleimide is thermally polymerized in a novolac type phenol resin (b) A polyimide resin is uniformly dispersed and mixed (B) An epoxy resin and (C) An inorganic filler is an essential component, and the polyimide resin is contained in a proportion of 0.01 to 30% by weight based on the entire resin composition, and the inorganic filler is contained in a proportion of 25 to 90% by weight. A sealing resin composition characterized by: 2. The resin mixture is novolac type phenolic resin 100
Bismaleimide is blended with 0.1 to 100 parts by weight per part by weight, and the bismaleimide is thermally polymerized in a novolac type phenol resin to form a polyimide resin, which is uniformly dispersed and mixed in the novolac type phenol resin. A sealing resin composition according to claim 1. 3. Claims in which the equivalent ratio [(i)/(ii)] between the epoxy group (i) of the epoxy resin and the phenolic hydroxyl group (ii) of the novolac type phenol resin is within the range of 0.1 to 10. The sealing resin composition according to item 1 or 2.