JPS6274980A - Method of bonding members for constituting semiconductor package - Google Patents

Abstract

PURPOSE:To obtain members for constituting a semiconductor package capable of preventing an adhesive from peeling off and having excellent sealing properties, by integrating two specified members among those for constituting a semiconductor package using an adhesive in a particular thickness. CONSTITUTION:A method of integrating two specified members among those for constituting a semiconductor package with an adhesive, wherein the adhesive is used in the following thickness. When an adhesive is interposed between a member 1 (e.g., cap) and a member 2 (e.g., substrate) to form a double-layer structure, the adhesive is used in a thickness X larger than that of equation I. When an adhesive is not interposed between the member 1 and the member 2, the thickness of the adhesive is as noted below. When equation II is established, the adhesive is used in a thickness X larger than that of equation III, while when equation IV is established, the adhesive is used in a thickness X larger than that of equation V. In the equations, alpha1, alpha2, and alpha3 are coefficients of linear expansion of the members 1 and 2 and the adhesive, respectively; E is the coefficient of longitudinal elasticity of the adhesive; nu is the Poisson ratio of the adhesive; tau1 and tau2 are the bonding strength between the adhesive and the member 1 and the one between the adhesive and the member 2, respectively; t is the temperature difference between the maximum temperature of an environment to which the semiconductor package is exposed and room temperature; and I0 is unit strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of bonding members constituting a semiconductor 1n package having a cavity structure.

[Conventional technology]

Conventionally, various methods of sealing semiconductors using adhesives have been studied as a method for forming seven cages for semiconductors having a cavity structure (for example, Utility Model Application Publication No. 49-132767).
Publication No.).

[Problem that the invention seeks to solve]

However, in the conventional method, when the cap, the substrate, and the adhesive have different coefficients of thermal expansion during curing of the adhesive or in a high-temperature environment such as during a heat resistance test, shear stress is generated at the interface between the cap and the adhesive and between the substrate and the adhesive. Since the adhesive was not thick enough to withstand this shearing stress, the adhesive peeled off from these interfaces, resulting in many failures in the Gross Leak (G/L) test for evaluating sealing properties.

The present invention aims to provide a method for bonding members constituting a semiconductor package that prevents such peeling of the adhesive and has excellent sealing properties.

Means for Solving Problem c] The present invention provides a method for integrating two members of the members constituting a semiconductor package using an adhesive.
The coefficient of linear expansion is αa, the coefficient of linear expansion of member 2 is α2, the coefficient of linear expansion of adhesive is αa, the modulus of longitudinal elasticity of adhesive is E, the Poisson's ratio of adhesive is v, the adhesion between adhesive and member l The intensity is τ
1. The adhesive strength between the adhesive and member 2 is τ2, the temperature difference between the highest environmental temperature to which the semiconductor puff cage is exposed and room temperature is t, and the unit length is 10, and the adhesive between member 1 and member 2 is In the case of a double bonded structure with an adhesive interposed, the thickness of the adhesive is at least X, and in the case of a structure with no adhesive interposed between member 1 and member 2, When α2: τ2, a semiconductor package is constructed in which at least the thickness of the adhesive is X, and the thickness of the adhesive is also X.

The present invention will be explained in detail with reference to the drawings. The present invention relates to a method of bonding members constituting a semiconductor package having a cavity structure, and here, as shown in FIG. This will be explained using a package sealing method as an example.

As shown in Figure 1, as a PGA sealing method, semiconductors 5
A cap 1 having a cavity 8 for housing the cap 1 and a substrate 2 having an external terminal pin 6 are sealed with an adhesive 3. 4 is a thin metal wire, and 9 is a circuit. The thickness of the adhesive 3 that can withstand the shear stress generated at the interfaces between the cap 1 and the adhesive 3 and between the substrate 2 and the adhesive 3 is determined by the thickness of the adhesive 3 that can withstand the shear stress generated at the interfaces between the cap 1 and the adhesive 3 and between the substrate 2 and the adhesive 3. I asked for it as. As a result, in a double bonded structure in which an adhesive 3 is interposed between a camp 1 and a substrate 2 as shown in FIG. The thickness xl of the adhesive 3 is also the thickness x2 of the adhesive 3 that can withstand the shear stress generated at the interface between the substrate 2 and the adhesive 3. Therefore, the minimum required thickness of the adhesive 3 is X=X electric + x2 = becomes.

In calculations, for the cap 1 and the substrate 2 made of various materials,
5 to 5 when the longitudinal elastic modulus E of the adhesive 3 is 5 to 30 kg/-
It is 400 μm. The longitudinal elastic modulus E was taken as the value at the highest environmental temperature to which the semiconductor package is exposed.

Next, a case where the adhesive 3 is not interposed between the cap 1 and the substrate 2 shown in FIG. 3 will be described. FIG. 3 shows the member 1 and the member 2 after the cap 1 having the cavity 8 for storing the semiconductor 5 and the substrate 2 are fitted and integrated.
The periphery of the fitting part is fixed with adhesive (hereinafter referred to as caulking method) so that the peripheral part of the fitting part is covered with adhesive 3. Third
The figure shows the case of α3−α2 τ2, and from FIG. 4, which models the caulking method, the thickness x2 of the adhesive 3 can be calculated as E(α1−αz
)t (.

1≧τ1/τ2 (1+ν) or more, that is, 200
The thickness may be at least μm.

The method of sealing the cap 1 and the substrate 2 with the adhesive 3 is as shown in FIG.
It is also possible to use a method of joining with an intermediary. Although the structure is a double weighted structure, there is no problem as long as the thickness X of the adhesive 3 of x and +X2 satisfies the above conditions.

By adhesively fixing the cap 1 and the substrate 2 with the adhesive 3 as described above, the cap 1, the substrate 2, and the adhesive 3 are
The shear stress caused by the difference in the thermal expansion coefficient of
As a result, the sealability of the package was improved without the adhesive peeling off.

Various types of caps 1 and substrates 2 used in the present invention can be used depending on the characteristics required for each semiconductor package. In addition to electrical and mechanical properties of a certain level or higher, it is also necessary to have moldability of a certain level or higher.

A typical example is thermoplastic resin, which can withstand the various reliability tests required for semiconductor packages.

Thermosetting resins, combinations of some of these resins with various fillers such as glass fiber and fused silica, ceramics such as alumina, metals such as aluminum, sapphire glass, and glasses such as borosilicate glass. can be mentioned.

Furthermore, although the above-mentioned example concerns the adhesion or sealing method between the cap and the substrate of a PGA type package, the present invention relates to the method of bonding, or sealing, the cap and the substrate of a PGA type package. An example of its application is a DIP sealing method in which a lead frame on which semiconductors are mounted is sandwiched between two plate-like bodies, at least one of which has a cavity, and then integrated with adhesive. , a thermoplastic resin package with a cavity inside (Special Publication No. 58-18
5), bonding of a thermoplastic resin plate-shaped molded product of an EPROM package and a window material for transmitting ultraviolet rays, bonding of a substrate and pin of a PGA package, and DIP, PGA
Examples include adhesion between the package and the heat sink.

Furthermore, the adhesive 3 is required to be able to withstand heat during joining and at high temperatures, and silicone-based, vinyl nitrile rubber, or polyurethane-based adhesives can be used.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

(Example 1, Comparative Example 1) Heat distortion temperature (ASTM D648.18.6 kg/d
A substrate 2 as shown in FIG. 3 is made of polyoxybenzoyl with a load of 300° C. or more, and an aluminum cap 1 is constructed so that no adhesive is interposed between the substrate 2 and the cap L, and a silicone adhesive is used. was applied to a height of 200 μm or more and fixed with adhesive to produce a PGA package.

Such a PGA package is heated between -55°C and 150°C for 50 minutes.
Although the test was repeated through 00 heating and cooling cycles, no deterioration in sealing performance was observed, and no deterioration was observed in the G/L test, so a PGA package with sufficient reliability was obtained.

On the other hand, a PGA obtained by using the same materials as in the above embodiment and bonding the cap 1 and the substrate 2 with the adhesive 3 interposed between the cap 1 and the substrate 2 with a thickness of 50 μm as shown in FIG. When the package was subjected to 2 to 3 cooling/heating cycles at temperatures ranging from -55°C to 150°C, peeling of the adhesive was observed.

Note that α and α2 are each 2.9 × 10”℃−
1,2,OX 10” °c-', E is 24 kg/
cJ, v is 0.5, τ1, τ2 are each 2466.
21.8, t is 125°c, to is l cm and the value is 180 μm.

(Example 2, Comparative Example 2) Heat distortion temperature (ASTM D648.18.6 kg/c
A thermoplastic resin plate-shaped molded product 10 having an opening window as shown in FIG.
A lid body 12 made of borosilicate glass is fitted to the lid body 12, and a structure is created in which no adhesive 3 is interposed between the plate-shaped molded product lO and the lid body 12 as shown in FIG.
It was applied and adhered to a height of On the other hand, a plate-shaped molded product with only a depression was made from the same resin, and the combined surfaces of the lower and upper lids were heated, and
EPRO by the method shown in Publication No. 85
They were integrated by sandwiching and applying pressure to the lead frame on which the M element was mounted.

Such an EPROM is heated at a temperature between -55°C and 150°C for 500°C.
Although the test was repeated through several cooling/heating cycles, no deterioration in sealing performance was observed, and no deterioration was observed in the G/L test, and an EPROM having sufficient reliability was obtained.

On the other hand, an EPROM obtained by using the same material as in the above example and bonding the upper lid and the lid with an adhesive interposed between them and the thickness of the adhesive is -55°C to 150°C.
Peeling of the adhesive was observed when the temperature was raised and lowered between 2 and 3 times and the temperature was cycled 2 to 3 times.

Note that α1 and α2 are each 3.95X10-6°
C-1,1,8X10-5℃ fence, E is 24kg/cJ,
ν is 0.5, τ8 and τ2 are respectively 28.1.24.3
, L is 125°C, and 10 is l cm. [Effects of the Invention] According to the present invention, the shear stress caused by the difference in thermal expansion coefficient between the adhesive and the member of the semiconductor package having a cavity structure is relaxed, and the adhesive peels off. This makes it possible to bond components of semiconductor packages with sufficient reliability even under environmental tests such as thermal cycles.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts of a PGA type package as an embodiment of the present invention, FIG. 2 is a model diagram of the double quantity balancing method,
Fig. 3 is a cross-sectional view of the main parts of a PGA type package using the caulking method as an embodiment of the present invention, Fig. 4 is a model diagram of the caulking method, and Fig. 5 is a double-layered structure using an adhesive sheet. The model diagram, FIG. 6, is a schematic cross-sectional view showing the state of adhesion between the lid and the thermoplastic resin plate-shaped molded product in the EOROM package. Explanation of symbols l Cap 1 (member 1) 2 Substrate (member 2) 3 Adhesive 4 Thin metal wire 5 Semiconductors
6 Pin 7 Adhesive sheet 8 Cavity 9 Circuit
10 Thermoplastic resin plate-shaped molded product 11 Step 12 Lid body agent Patent attorney Kunihiko Wakabayashi − Ke −−

Claims (1)

[Claims] 1. In a method of integrating two members constituting a semiconductor package with an adhesive, the coefficient of linear expansion of member 1 is α_1, and the coefficient of linear expansion of member 2 is α_2. , the coefficient of linear expansion of the adhesive is α_a, the modulus of longitudinal elasticity of the adhesive is E, the Poisson's ratio of the adhesive is v, the adhesive strength between the adhesive and member 1 is τ_1, the adhesive strength between the adhesive and member 2 is τ_2 , and the temperature difference between the highest environmental temperature to which the semiconductor package is exposed and the room temperature is t, and the unit length is l_0. , at least the adhesive thickness x
But Etl_0/2(l+v){α_a−α_1/τ_1+
α_a-α_2/τ_2} or more; (B) In the case of a structure in which no adhesive is interposed between member 1 and member 2, (B) α_a-α_1/α_a-α_1≧τ_1/τ_
2, at least the thickness x of the adhesive is E(α_a-α_1)/2τ_1(1+v)<0 or more, and (b) α_a-α_1/α_a-α_2<τ_1/τ_
2, a method for bonding members constituting a semiconductor package, characterized in that at least the thickness x of the adhesive is E(α_a−α_2)/2τ_2(1+v)<0 or more.