Flip-chip type semiconductor device sealing material

Details Flip-chip type semiconductor device sealing material Flip-chip type semiconductor device sealing material

2000-02-07

2001-10-30

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C257S789000, C257S793000, C257S795000

Reexamination Certificate

active

06310120

ABSTRACT:

This invention relates to a flip-chip type semiconductor device sealing material, especially suited for use as an underfill material so that the filled state is readily ascertainable.
BACKGROUND OF THE INVENTION
With the advance of electric equipment toward smaller size, lighter weight and higher performance, the semiconductor mounting technology has changed from the pin mating type to the surface mounting which now becomes the mainstream. One bare chip mounting technology is flip-chip (FC) mounting. The flip-chip mounting is a technique of providing an LSI chip on its circuit pattern-bearing surface with several to several thousands of electrodes, known as bumps, of about 10 to 100 microns high and joining the chip to electrodes on a substrate with a conductive paste or solder. Then the sealing material used for the protection of FC devices must penetrate into gaps of several tens of microns defined by bumps between the substrate and the LSI chip. Since the resin underfill system requires to fill very narrow gaps with the resin, voids and shorts are often left. It is thus strongly desired to quickly detect such defects in a continuous manner so that defective parts may be eliminated.
In the prior art, an ultrasonic flaw detector is generally used for the detection of defects in devices sealed by the resin underfill method. Although the ultrasonic flaw detector can detect very small defects, it is unamenable to automatic detection, imposing a limit on the quickness of defect detection.
For conventional semiconductor devices, a soft x-ray detector is widely employed for the purpose of detecting wire flow or wire breakage. Where flip-chip type semiconductor devices are sealed with an underfill material using silica as an inorganic filler, the resin layer is so thin that it may become difficult to discriminate voids from the resin with soft x-rays.
SUMMARY OF THE INVENTION
An object of the invention is to provide a flip-chip type semiconductor device sealing material which allows for easy detection of defects with soft x-rays and improves the reliability of the flip-chip type semiconductor device.
It has been found that when a liquid epoxy resin is blended with a specific proportion of a soft x-ray non-transmissive spherical inorganic filler, preferably having a maximum particle diameter of up to 25 &mgr;m and a mean particle diameter of 1 to 5 &mgr;m, the resulting underfill material effectively infiltrates into narrow gaps and facilitates automatic detection of defective parts using soft x-rays. Then the filled state of the underfill material is previously ascertainable, and defective parts are readily sorted out. This contributes to the manufacture of highly reliable semiconductor devices.
Accordingly the invention provides a flip-chip type semiconductor device sealing material comprising
(A) 100 parts by weight of a liquid epoxy resin,
(B) 0 to 100 parts by weight of a curing agent,
(C) 50 to 300 parts by weight of spherical silica per 100 parts by weight of components (A) and (B) combined,
(D) an effective amount to prohibit transmission of soft x-rays of a soft x-ray non-transmissive spherical inorganic filler, and
(E) 0.01 to 10 parts by weight of a curing accelerator per 100 parts by weight of components (A) and (B) combined.


REFERENCES:
patent: 4999699 (1991-03-01), Christie et al.
patent: 5089440 (1992-02-01), Christie et al.
patent: 5292688 (1994-03-01), Hsiao et al.
patent: 5928595 (1999-07-01), Knapp et al.
patent: 6018196 (2000-01-01), Noddin
patent: 07041544 (1995-02-01), None

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