JPH0637546B2 - Sealing resin composition - Google Patents

Description

Detailed description of the invention [Industrial application] The present invention relates to a sealing resin composition having excellent moisture resistance and solder heat resistance.

(Prior Art) In recent years, in the field of semiconductor integrated circuits, along with technological development of high integration and high reliability, automation of a mounting process of a semiconductor device has been promoted. For example, when attaching a flat package type semiconductor device to a circuit board, conventionally, each lead pin was soldered, but recently, the entire semiconductor device is dipped in a solder bath heated to 250 ° C or more to perform soldering. The method has been adopted.

(Problems to be Solved by the Invention) In a semiconductor device sealed with a conventional resin composition composed of an epoxy resin, a novolac-type phenol resin, and silica powder, when the entire device is immersed in a solder bath, moisture resistance is lowered. There was a flaw. In particular, when a semiconductor device that has absorbed moisture is dipped in solder, peeling occurs between the encapsulating resin and the semiconductor chip and frame, causing a significant deterioration in moisture resistance, causing wire breakage due to electrode corrosion and leak current due to moisture, and The drawback is that reliability cannot be guaranteed.
Therefore, there has been a strong demand for the development of a sealing resin that is less affected by moisture absorption and has less moisture resistance deterioration even when the entire device is immersed in a solder bath.

The present invention has been made in order to solve the above-mentioned drawbacks and to meet the demand, and has a small influence of moisture absorption, and particularly provides a sealing resin composition having excellent moisture resistance and solder heat resistance after immersion in a solder bath. Is what you are trying to do.

[Structure of the Invention] (Means and Actions for Solving Problems) As a result of intensive studies to achieve the above object, the present inventor has found that organosilicon having a phosphate group and a specific amount of silica powder are used. It was found that a resin composition excellent in moisture resistance and solder heat resistance can be obtained by blending, and the present invention has been completed. That is, the present invention includes (A) an epoxy resin, (B) a novolac-type phenol resin, (C) a phosphoric acid group-containing organosilicone, and (D) a silica powder. A resin composition for encapsulation, which contains silica powder in a proportion of 65 to 85% by weight.

The (A) epoxy resin used in the present invention is not particularly limited in molecular structure, molecular weight, etc., as long as it is a compound having at least two epoxy groups in the molecule, and widely used resins are widely used. You can Examples thereof include bisphenol type aromatic resins, alicyclic resins such as cyclohexane derivatives, and epoxy novolac resins represented by the following general formula.

(In the formula, R ¹ represents a hydrogen atom, a halogen atom or an alkyl group, R ² represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) These epoxy resins may be used alone or in a mixture of 2 or more kinds. To use as.

The novolak type phenolic resin (B) used in the present invention is a novolak type phenolic resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde,
Further, modified resins thereof, such as epoxidized or butylated novolac type phenolic resin, silicone modified phenolic resin and the like can be mentioned, and they can be widely used without particular limitation as long as they are novolac type phenolic resins.
And these novolac type phenol resins are used individually or as a mixed system of two or more kinds.

The organosilcon having a phosphate group (C) used in the present invention is represented by the following general formula.

(However, in the formula, R represents a methyl group or a phenyl group,
Represents an integer of 1 or more) The ratio of 1 / m is not particularly limited, but if it is less than 0.01, the effect of the phosphoric acid group becomes insufficient and the adhesiveness decreases, which is not preferable. The organosilicon preferably has a molecular weight of 60,000 or less, and if it exceeds this range, the organosilcon is not sufficiently dispersed, which is not preferable. By using the organosilicon having a phosphoric acid group, the adhesiveness between the encapsulating resin and the semiconductor chip and the adhesiveness between the encapsulating resin and the lead frame are improved, and the moisture resistance deteriorates even when immersed in a solder bath. Few. It also has excellent adhesion to the passivation film. This improvement in adhesion is effective in the case of a design standard in which the ratio of chip area / package area approaches 1.

The (D) silica powder used in the present invention may be a commercially available one, but it is preferably one having a low impurity concentration and an average particle size of 30 μm or less. If the average particle size exceeds 30 μm, the moisture resistance and the moldability are poor, which is not preferable. The blending ratio of silica powder is 65 to 85% by weight based on the resin composition.
It is preferable to contain it in a ratio of. If the blending amount is less than 65% by weight, the resin composition has large hygroscopicity and is inferior in moisture resistance after solder immersion, and if it exceeds 85% by weight, fluidity is extremely poor and moldability is inferior. Therefore, it is limited to the above range.

The resin composition of the present invention contains an epoxy resin, a novolac-type phenol resin, an organosilicon having a phosphoric acid group and silica powder, and if necessary, for example, natural waxes, synthetic waxes, metal salts of straight chain fatty acids. , Release agents such as acid amides, esters and paraffins, flame retardants such as antimony trioxide, colorants such as carbon black, silane coupling agents, various curing accelerators, etc. may be appropriately added and blended. it can.

As a general method for preparing the resin composition of the present invention as a molding material, an epoxy resin, a novolac type phenol resin, an organosilicon having a phosphoric acid group, silica powder, and other components are blended and mixed by a mixer or the like. After sufficiently homogeneously mixing, a melt mixing process using a hot roll or a mixing process using a kneader or the like is further performed, followed by cooling and solidification, and crushing to an appropriate size to obtain a molding material. Then, these molding materials can be applied to the sealing, coating, insulation, etc. of electronic parts or electric parts to impart excellent characteristics and reliability.

(Examples) Hereinafter, examples of the present invention will be described together with comparative examples, but the present invention is not limited to the following examples.

EXAMPLE According to the composition shown in Table 1, epoxy resin, novolac type phenol resin, organosilicon having phosphoric acid group, silica powder and curing accelerator, mold release agent, silane coupling agent, etc. were mixed at room temperature, and The mixture was kneaded at 90 to 95 ° C, cooled, and then pulverized to obtain a molding material. Transfer the obtained molding material into a mold heated to 170 ° C.,
It was cured to make a sealed molding. The molded product was tested for water absorption, glass transition temperature and moisture resistance after solder immersion, and the results are shown in Table 1. The molded product obtained from the encapsulating resin composition of the present invention had a small water absorption rate and excellent moisture resistance, and the remarkable effect of the present invention was confirmed.

Comparative Examples 1 and 2 According to the compositions shown in Table 1, molding materials were obtained in the same manner as in Examples to form molded articles, and the same tests as in Examples were carried out.
The results are shown in Table 1.

The water absorption rate, the glass transition temperature, and the moisture resistance after solder immersion, which were tested in Examples and Comparative Examples, were tested as follows. The water absorption rate is 50 by the transfer molding.
A molded product having a thickness of 3 mm and a thickness of 3 mm was prepared, and the molded product was allowed to stand in a saturated steam pressure of 2.5 atm at 127 ° C. for 24 hours, and the weight was increased. The glass transition temperature was measured by using a thermomechanical analyzer by making a molded article which was the same as in the water absorption test and subjecting this to post-curing at 175 ° C. for 8 hours to obtain a test piece of an appropriate size. Moisture resistance is measured by bonding a silicon chip (test element) having two or more aluminum wirings to a normal 42 alloy frame using a sealing resin composition and transfer molding at 175 ° C. for 2 minutes. 5 x 10 x
A 1.5 mm flat package type molded product (sealed product) was obtained and then post-cured at 175 ° C. for 8 hours. This molded product is subjected to moisture absorption treatment at 40 ° C, 90RH, 100 hours in advance, then 250
It was soaked in a solder bath at ℃ for 10 seconds. Next, in a saturated steam at 127 ° C and 2.5 atmospheres, pressure cooker test (PC
T) was performed, and the disconnection due to the corrosion of the aluminum wiring was evaluated as defective, and the test was conducted.

[Effects of the Invention] As is clear from the above description and Table 1, the encapsulating resin composition of the present invention has good adhesiveness, and therefore has little influence of moisture absorption, and has moisture resistance even after being immersed in a solder bath. In addition, it is possible to remarkably reduce disconnection due to corrosion of electrodes and generation of leak current due to moisture, and as a result, reliability can be guaranteed for a long period of time. It also showed excellent heat resistance despite immersion in a solder bath at 250 ° C or higher.

Claims (1)

[Claims] 1. (A) Epoxy resin (B) Novolac type phenolic resin (C) Organosilicon having a phosphate group represented by the following general formula and (However, in the formula, R is a methyl group, a phenyl group, 1, m, n
Represents an integer of 1 or more) (D) Silica powder is contained, and the (D) silica powder is contained in a proportion of 65 to 85% by weight with respect to the entire resin composition. Resin composition.