JP2834841B2 - High heat resistant resin encapsulated semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial Application Field) The present invention relates to a high heat-resistant resin-sealed semiconductor device, and particularly to a high heat-resistant resin-sealed package having no cracks even when heated at 200 ° C. or more. The present invention relates to a semiconductor device.

(Prior Art) In general, the overall structure of a high heat-resistant resin-sealed semiconductor device in which a semiconductor chip is fixed on a lead frame island with a die bonding material is as shown in FIG.

In this figure, 1 is an external lead, 2 is an island,
Reference numeral 3 denotes a semiconductor chip, 4 denotes a bonding wire, 5 denotes a cured die bonding material, 6 denotes a mold resin, and 7 denotes a vent hole.

Here, the vent hole 7 is formed by forming a column or a polygonal column in the mold resin portion on the back surface of the island 2 to form an extremely thin portion or a portion having no mold resin. It plays a role of releasing gas due to evaporation of moisture around the semiconductor chip.

(Problems to be Solved by the Invention) However, in the above-described conventional semiconductor device, the die bonding material for fixing the semiconductor chip on the island of the lead frame is Au-Si eutectic. With the increase in size, die bonding materials have shifted to organic polymer materials such as epoxy, polyimide, and silicone. The use of such an organic polymer material lowers the solder heat resistance because the material itself has lower heat resistance than the Au-Si eutectic. For this reason,
When the semiconductor device receives heat, the resin itself of the die-bonding material expands greatly, and the mold resin portion of the island portion is deformed and cracks are formed. It is difficult to release moisture. In particular, such defects appear due to heating performed at the time of mounting the semiconductor device on the printed circuit board, for example, a heating process by IR (infrared) reflow performed at 200 ° C. or higher.

FIG. 5 is a cross-sectional view of a normal conventional semiconductor device having no defect, and FIG. 6 is a cross-sectional view of a semiconductor device having a defect.

The present invention eliminates the above-mentioned problems, and in a resin-encapsulated semiconductor device using an organic polymer material as a die bonding material, prevents deformation and cracking of a package due to heating at 200 ° C. or more when mounting a substrate. It is an object of the present invention to provide a highly heat-resistant resin-encapsulated semiconductor device that can be used.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a semiconductor chip fixed to an island portion of a lead frame via an organic polymer adhesive as a die bonding material, and a sealing resin. In a sealed resin-sealed semiconductor device, the cured adhesive has a modulus of elasticity of 200 ° C. or more of 4 × 10 ⁹ dyn / cm ² or more, and is left at 85 ° C./85% RH (relative humidity) for 72 hours. In this case, an organic polymer adhesive having a moisture absorption of 0.2% or less is used.

(Operation) In the expansion deformation of the die bonding layer, the factor causing the deformation is mainly the thermal expansion coefficient, while the factor preventing the deformation is mainly the elastic modulus. However, the elastic modulus decreases in the rubbery region which is equal to or higher than the glass transition point of the die bonding material resin. More specifically, the elastic modulus decreases to about 1/10 with respect to room temperature at 200 ° C. or higher. Becomes easily deformed. Therefore, a die bonding material having a high elastic modulus at 200 ° C. or more is useful for preventing the die bonding layer from expanding and deforming.

Further, when the moisture absorbed by the die bonding layer and the moisture agglomerated on the interface having weak adhesiveness are exposed to a high temperature of 200 ° C. or more, an external force which evaporates and expands and causes the die bonding layer to undergo plastic deformation as shown in FIG. Becomes Therefore, the die bonding material needs to be a resin that hardly contains moisture, that is, a resin having a low moisture absorption rate.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a highly heat-resistant resin-sealed semiconductor device of the present invention.

As shown in the figure, the following materials are used as the die bonding material 10 for die bonding of the semiconductor chip 3 on the island of the lead frame. That is, as an adhesive to the island 2 of the lead frame of the semiconductor chip 3, five types of epoxy resins A to E having different compositions and a polyimide resin are bonded and used as a die bonding material, and resin sealing is performed. A semiconductor device was fabricated. The compositions of the epoxy resins A to E shown in FIG. 2 were used. Table 1 shows the number of cracks generated in the package of the semiconductor device when the manufactured semiconductor device was subjected to heat treatment by IR reflow at 240 ° C. after being left in an atmosphere of 85 ° C./85% RH for 30 hours and 72 hours. Show.

In Table 1, the chip size is 8.0 × 8.0 mm ² 100p package 20 mm × 14 mm × 2.75 mm From Table 1, it can be seen that the cured epoxy resins A and B are excellent without cracks.

When the storage modulus of each of the epoxy resin cured products A to E was measured with respect to the change in temperature, the graph shown in FIG. 3 was obtained. As is clear from FIG. 3, the epoxy resin cured products A and B showing excellent curing in Table 1 have a storage elastic modulus of 4 × 10 ⁹ dyn / cm ² or more even at a temperature of 200 ° C. or more. I understand.

Further, FIG. 4 is a graph showing the results of measuring the change in the moisture absorption of each of the cured epoxy resins A to E and the cured polyimide resin with respect to the standing time in a 85 ° C./85% RH atmosphere with respect to the cured resin.

As is clear from this figure, it is understood that the epoxy resin cured products A and B, which exhibited excellent effects in Table 1, have a moisture absorption of 0.2% or less.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the gist of the present invention.
They are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the elastic modulus of the cured resin at 200 ° C or more is 4 × 10 ⁹ dyn / cm ² or more, and 85 ° C / 85% RH. Moisture absorption after leaving for 72 hours at 0.2%
By using the following cured resin, deformation of the package of the resin-encapsulated semiconductor device and generation of cracks in the package can be prevented even by heating at 200 ° C. or more when the substrate is mounted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a highly heat-resistant resin-sealed semiconductor device showing an embodiment of the present invention, and FIG. 2 is a diagram showing a composition of an epoxy resin used in the embodiment of the present invention. Fig. 3 shows the temperature of the cured resin-
FIG. 4 is a diagram showing time-moisture absorption characteristics of a cured resin, FIG. 5 is a cross-sectional view of a conventional resin-encapsulated semiconductor device, and FIG. 6 is a conventional resin having defects. It is sectional drawing of a sealing type semiconductor device. 2 ... Island, 3 ... Semiconductor chip, 10 ... Die bonding material.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/52 H01L 23/30

Claims (1)

(57) [Claims] 1. A resin-encapsulated semiconductor device in which an organic polymer adhesive is used as a die-bonding material for die-bonding a semiconductor chip on an island of a lead frame and is sealed with a sealing resin. Using an organic polymer adhesive having a modulus of elasticity at 200 ° C or higher of 4 × 10 ⁹ dyn / cm ² or higher and a moisture absorption of 0.2% or lower after standing at 85 ° C / 85% RH for 72 hours. A highly heat-resistant resin-sealed semiconductor device characterized by the following.