Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Flip chip
Reexamination Certificate
2000-08-30
2002-10-01
Talbott, David L. (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Flip chip
C257S787000, C264S272110, C264S272150, C264S272170
Reexamination Certificate
active
06459159
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin sealing method and apparatus for a semiconductor device. More particularly, the invention relates to a resin sealing method and apparatus which are well adaptable for the resin sealing of a semiconductor device having an underfill structure, e.g., a semiconductor device including a flip-chip connected semiconductor chip.
2. Description of the Related Art
A semiconductor device having a semiconductor chip mounted by a flip chip method is shown in FIG.
16
. As shown, a semiconductor chip
12
is flip-chip connected onto a substrate
10
, and then a joining portion between the semiconductor chip
12
and the substrate
10
is filled with sealing resin
14
, to thereby seal the joining portion by resin. The sealing resin
14
functions to protect the joining portion between the semiconductor chip
12
and the substrate
10
and to relieve a thermal stress caused by the thermal coefficient difference of expansion between the substrate
10
and the semiconductor chip
12
.
A known method of filling the joining portion with resin
14
, generally used, is shown in FIG.
17
. As shown, the substrate
10
is slantly supported, and in this state, sealing resin
14
is allowed to flow into the joining portion between the substrate
10
and the semiconductor chip
12
. A number of solder bumps
16
are studded on the joining portion between the substrate
10
and the semiconductor chip
12
. The sealing resin
14
flows through gaps among those bumps
16
. To make the flow of the sealing resin easy, the substrate
10
is slanted, and the sealing resin
14
flows onto the slanted substrate
10
while expelling air from the joining portion.
When the sealing resin
14
is allowed to merely flow into the joining portion of the flip-chip connected semiconductor chip
12
to fill out there, the sealing resin
14
imperfectly fills the joining portion between the semiconductor chip
12
, and sometimes the substrate
10
and air bubbles are left in the gap portion. Actually, the width of the joining portion (between the semiconductor chip
12
and the substrate
10
) is about 0.1 mm, and recently it is reduced from 0.1 mm to 0.02 mm to 0.03 mm, extremely narrow. A number of solder bumps
16
are studded in the joining portion, and those bumps restrict the flow of the sealing resin
14
. When the filler-contained resin is used, the resin flow is further impeded. Therefore, the method of merely flowing the sealing resin
14
into the underfilled portion cannot achieve the reliable sealing. A resin hardening time in the potting process is longer than in the transfer molding process. Therefore, also in the work efficiency, the method by merely flowing the sealing resin
14
into the underfilled portion is not preferable.
The solder bumps are minutely different in height and the semiconductor chips are also minutely different in thickness with the pieces to be molded. Therefore, when the transfer molding is used for sealing flip-chip connected semiconductor chip by resin, the following disadvantages are present: 1) a thin layer of resin will be formed on the outer surface of the semiconductor chip; and 2) the resin excessively presses the molded piece to possibly break the molded piece. Further, the resin material including extremely small silica particles or not including the same must be used since the gaps in the underfilled portion are extremely small. Such a resin material is easy to enter the gaps. Therefore, if the clamping of the molded piece is not properly, the resin will enter the gaps to form resin flash. The same disadvantageous phenomenon occurs also when the semiconductor chip is minutely displaced (when viewed in plan) on the substrate. For this reason, it is almost impossible to resin seal the underfilled portion resulting from the flip-chip connection by the conventional transfer molding process.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a resin sealing method for sealing a semiconductor device with resin which is improved such that a transfer molding process is used for manufacturing a semiconductor device having an underfill structure, e.g., a semiconductor device including a flip-chip connected semiconductor chip, and the use of the transfer molding process provides a reliable underfilling free from air bubbles and produces a reliable semiconductor device, and an efficient underfilling process is provided.
Another object of the invention is to provide a resin sealing apparatus achieving the same improvements as by the resin sealing method.
To achieve the above object, the present invention has the following constructions:
A resin sealing method for a semiconductor device for sealing a molded piece including a semiconductor chip with resin by a transfer molding process in a state that the molded piece is clamped by a mold, the method comprises the steps of:
covering a clamping surface of the mold for clamping the molded piece and sealing resin material with a release film;
clamping the molded piece and sealing resin material with the release film placed therebetween, and clamping the resin material through an urging means for urging the resin material in the mold closing direction; and
feeding molten resin to the molded piece under pressure by the urging force of the urging means, thereby filling the molded piece with the resin material.
In the resin sealing method, the resin material takes the form of a cylindrical resin tablet, and the resin tablet is placed while being laid down on the clamping surface of the mold, whereby the resin filling is performed.
A resin sealing apparatus for a semiconductor device for sealing a molded piece including a semiconductor chip with resin by a transfer molding process in a state that the molded piece and sealing resin material are clamped by a mold, through a release film covering a clamping surface of the mold, the resin sealing apparatus is characterized in that a mold portion of the mold for clamping the resin material is supported movably in the mold opening and closing directions, and urged in the mold closing direction by an urging means so as to be able to feed molten resin under pressure.
In the resin sealing apparatus, the surface of the mold portion for pressing the resin material is arcuately curved inward in cross section, the resin material being laid down on the surface of the mold portion.
Further, the mold portion is a cull insert with a spring as the urging means, and a center block is fixed at a location opposed to the cull insert.
A resin sealing method for sealing a joining portion between a semiconductor chip and a substrate by feeding pressurized sealing resin to an underfilled portion of a molded piece in which a semiconductor chip is mounted on a-substrate, thereby sealing the joining portion, the method is characterized in that when the molded piece is clamped with a mold, the perimeter of the underfilled portion, except a portion to which a gate continuous to the underfilled portion is connected, is closed with a release film, and in a state that the perimeter of the underfilled portion is closed, the sealing resin is fed under pressure to the underfilled portion, to thereby fill the underfilled portion.
In the resin sealing method, when the underfilled portion is closed by the release film, the film is pressed against the side face of the semiconductor chip, whereby only the interior of the underfilled portion is filled with the sealing resin.
Further, when the underfilled portion is closed by the release film, the film is pressed against the side face of the semiconductor chip, through an elastic member elastically deformable when it receives a clamping force for clamping the molded piece.
When the underfilled portion is closed by the release film, the sealing resin fills out side-face sealing portions provided between the side faces of the semiconductor chip. and the release film, and the underfilled portion.
When the underfilled portion is filled with the sealing resin, the s
Aoki Kunihiro
Kodama Masahiro
Miyagawa Tsutomu
Miyajima Fumio
Apic Yamada Corporation
Chambliss Alonzo
Sughrue & Mion, PLLC
Talbott David L.
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