Stock material or miscellaneous articles – Layer or component removable to expose adhesive
Reexamination Certificate
2002-07-03
2004-08-31
Zirker, Daniel (Department: 1771)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
C428S343000, C428S328000, C428S329000, C428S330000, C428S354000, C428S3550CN, C428S3550EP, C428S3550EN, C428S402000, C428S474400
Reexamination Certificate
active
06783828
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to resin compositions and particularly to resin compositions used for semiconductor devices, which must have excellent electrical and mechanical characteristics. Specifically, the present invention relates to an adhesive used for semiconductor devices. More specifically, the present invention relates to an adhesive film used in tape automated bonding (TAB), which is a method for packaging semiconductor devices, to an adhesive sheet used for bonding semiconductor integrated circuits to an interposer, which is a substrate for connecting semiconductor integrated circuits, in order to package the circuits by wire bonding, and to a semiconductor device using the adhesive film and sheet.
2. Description of the Related Art
In general, as ambient temperature increases, resin molecules become active, so that the length and the volume of the resin increase and the elastic modulus deteriorates. Resin compositions whose size and elastic modulus easily change, traditionally, cannot be used in high-precision processing. Also, when a resin composition laminated with a different material, such as, metals or ceramics, is subjected to, for example, a heat cycle test in which heating and cooling are repeated, the difference between the thermal expansion coefficients of the resin composition and the different materials causes an internal stress and degrades elasticity. As a result, the adhesion between the laminated layers is degraded and, in some cases, delamination occurs. In addition, resin compositions used as adhesives for semiconductor devices are required to have sufficient adhesion even under conditions during the heat cycle test and reflow soldering.
It is known that degrading the elastic modulus of the resin compositions increases the adhesion of the resin compositions. However, this leads to an increased thermal expansion coefficient and the elastic modulus is significantly reduced at high temperature. As a result, the adhesion is degraded and the solder reflow resistance is poor.
On the other hand, in order to reduce the thermal expansion coefficient and to increase the elastic modulus of the resin compositions, the cross-linking density of the resin compositions is increased or a hard structure, such as benzene ring, is introduced. These methods are effective to increase the elastic modulus but do not sufficiently reduce the thermal expansion coefficient. As a result, shrinkage on curing of the resin compositions increase internal stress and the increased elastic modulus easily causes brittle fracture to occur in the adhesive resin composition. Thus, the adhesion of the resin compositions is degraded. Also, in another method, glass fiber, inorganic particles of silicon oxide, or the like are added to a resin material whose elastic modulus is low at room temperature to reduce the thermal expansion coefficient and to increase the elastic modulus at high temperature of the resin composition. However, in this instance, a large amount of inorganic component have to be added, and consequently the proportion of organic components is relatively reduced, so that the resulting resin composition becomes brittle and the adhesion of the resin composition is significantly degraded.
FIGS. 1-6
are TEM pictures of resin composition showing a matrix phase and a disperse phase. The TEM pictures include the magnification scale.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a highly adhesive resin composition having a high solder-reflow resistance, a low thermal expansion coefficient, and a high elastic modulus.
The present invention is directed to a resin composition comprising: a phase separation structure having at least two phases; and inorganic particles having a mean primary particle size of 0.1 &mgr;m or less.
The content of the inorganic particles may be in the range of 5 to 50 weight percent.
Preferably, the phase separation structure comprises a matrix phase and a disperse phase.
Preferably, the inorganic particles are mainly present in either the matrix phase or the disperse phase.
Alternatively, the inorganic particles may be mainly present in the interface between the matrix phase and the disperse phase.
Preferably, at least one of the matrix phase and the disperse phase forms a chain structure.
Preferably, the area ratio of the matrix phase is in the range of 50 to 95 and the area ratio of the disperse phase is in the range of 5 to 50.
Preferably, the elastic modulus of the resin composition after being cured is 25 MPa or more at a temperature of 150° C.
Preferably, the ratio of the elastic modulus of the resin composition at 30° C. to the elastic modulus at 150° C. is 30 or less.
The present invention is also directed to an adhesive film for semiconductor devices. The adhesive film comprises an organic insulating layer and an adhesive layer formed on a surface of the organic insulating layer. The adhesive layer comprises the resin composition described above.
The adhesive film may further comprise a protective layer capable of being peeled.
The present invention is also directed to a metallic foil-laminated film comprising the above-described adhesive film and a metallic foil laminated on the adhesive layer of the adhesive film.
The present invention is also directed to a semiconductor device comprising the metallic foil-laminated film.
By using the resin composition of the present invention, which has a low thermal expansion coefficient and a high elastic modulus, as an adhesive for semiconductor devices, a semiconductor device including an adhesive layer having excellent reflow soldering resistance and adhesion can be achieved.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A resin composition of the present invention has a phase separation structure between at least two phases and contains inorganic particles having a mean primary particle size of 0.1 &mgr;m or less.
The inorganic particles are not limited to being spherical but may be elliptical, flake, rod-like, or fibrous. The mean primary particle size of the inorganic particles is 0.1 &mgr;m or less and preferably in the range of 1 nm to 0.08 &mgr;m. A mean primary particle size larger than 0.1 &mgr;m makes it difficult to reduce the thermal expansion coefficient of the resin composition and to increase the elastic modulus. The mean primary particle size here means the highest frequency in the particle size distribution of the inorganic particles when they exist independently. The mean primary particle size also represents the diameter of the particles when they are spherical and the maximum length when they are elliptical or flat. When the particles are rod-like or fibrous, the mean primary particle size represents the maximum length in the longitudinal direction of the particles. The mean primary particle size of inorganic particle powder can be measured by a laser diffraction/scattering method or a dynamic light scattering method. However, the measuring method needs to be appropriately selected depending on the particle shape, the method for preparing the particles, the medium for dispersing the particles, and the method for dispersing the inorganic particles.
The content of the inorganic particles is in the range of 5 to 50 weight percent relative to the solid contents in the resin composition and preferably in the range of 7 to 30 weight percent. A content of the inorganic particles smaller than 5 weight percent makes it difficult to reduce the thermal expansion coefficient of resin composition and to increase the elastic modulus. A content of the inorganic particles more than 50 weight percent gradually degrades the adhesion of the resin composition.
Any inorganic particles including ceramics may be used in the present invention. Exemplary ceramic particles include simple ceramic powder, powder mixture of glass and ceramics, and crystallized glass.
Simple ceramic powder includes alumina (Al
2
O
3
), zirconia (ZrO
2
), magnesia (MgO), beryllia (BeO), mullite (3Al
2
O
3
.2SiO
2
), cordierite (5SiO
2
.2Al
2
O
3
Fujimaru Koichi
Matsumura Nobuo
Yoshimura Toshio
Morrison & Foerster / LLP
Toray Industries Inc.
Zirker Daniel
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