Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1997-06-25
2000-08-08
Mayes, Curtis
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156246, 156261, 156285, 156312, 156510, 156517, 29832, 29841, 29740, B32B 3100, B32B 3500, B23P 1900, H05K 330
Patent
active
060996781
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a laminating method of a film-shaped organic die-bonding material, a die-bonding method, a laminating machine and a die-bonding apparatus for the bonding of a semiconductor element (hereinafter referred to as "chip") onto a support member such as a leadframe using the film-shaped organic die-bonding material.
BACKGROUND ART
As a method for bonding a chip on a leadframe, it has heretofore been the practice to feed a die-bonding material onto the leadframe and then to bond the chip onto the leadframe. As such die-bonding materials, Au--Si eutectic, solders, resin pastes and the like are known, for example. Among these, Au--Si eutectic has the problems that it is costly and has a high modulus of elasticity and requires vibrations at portions to be bonded. Solders involve the problems that they cannot withstand temperatures equal to and higher than their melting point and they have a high modulus of elasticity. Of resin pastes, silver paste is most common. Compared with other materials, silver paste is most inexpensive and has high heat-resistant reliability and a low modulus of elasticity, which means that silver paste is used most often as a bonding material for IC and LSI leadframes.
Reflecting the high densification and the move toward larger chips in recent years, it has however become increasingly difficult to evenly coat silver paste over an entire surface upon bonding. Unless resin paste can be coated evenly, voids occur in bonded parts and upon mounting, they cause package cracking during the course of soldering heat treatment. Occurrence of such voids has therefore become a problem.
Further, there has been an ever-increasing demand in recent years for high-density mounting to meet the move toward smaller and/or thinner electronic equipment. Replacing semiconductor packages of the conventional pin insertion type, surface-mount semiconductor packages suited for high-density mounting have come into mainstream use.
In the case of a surface-mount package, leads are directly soldered to a printed circuit board or the like. Therefore, using infrared reflowing, vapor phase reflowing, solder dipping or the like as a heating method, the package is heated in its entirety and is then mounted.
Here, the entire package is exposed to temperatures as high as 210 to 260.degree. C. If moisture exists inside the package, package cracking (hereinafter called "reflow cracking") occurs as a result of explosive vaporization of the moisture.
This reflow cracking significantly reduces the reliability of the semiconductor package to the extent that it has become a serious problem and the subject of technical attention.
The following is the mechanism of the occurrence of reflow cracking caused by a die-bonding material. In a semiconductor package, (1) the die-bonding material absorbs moisture during storage, (2) upon mounting the package by reflow soldering, the moisture is vaporized by heat, (3) destruction or separation of the die-bonding layer takes place due to the resulting vapor pressure, and (4) reflow cracking then occurs.
Under the current circumstances whereby sealing materials have been increasingly improved in reflow cracking resistance, reflow cracking which is caused by a die-bonding material has become a serious problem, especially in thin packages, leading to a strong demand for the improvement of reflow cracking resistance.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a laminating method, a die-bonding method, a laminating machine and a die-bonding apparatus, which make it possible to fabricate, with good productivity, semiconductor packages which are free from package cracking and have excellent reliability.
Another object of the present invention is to provide a semiconductor device, which makes use of a film-shaped organic die-bonding material, is free from reflow cracking and has excellent reliability, and a fabrication process thereof.
In the present invention, a film-shaped organic die-bonding material is used. This is in th
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Kageyama Akira
Kaneda Aizou
Kikuchi Tooru
Kotato Akio
Maekawa Iwao
Hitachi Chemical Company Ltd.
Mayes Curtis
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