Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Reexamination Certificate
2001-02-12
2004-01-13
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
C264S272140, C264S272150, C264S272170, C264S276000
Reexamination Certificate
active
06676885
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a resin-molding method, molding dies and a circuit base member and more particularly to a transfer molding technique, wherein plural semiconductor devices are bonded onto one face of a single circuit board for subsequent batch resin encapsulation of the plural semiconductor devices in a single cavity formed by molding dies.
The transfer mold has most-widely been used for the resin-encapsulation technique of semiconductor devices, wherein the plural semiconductor devices are bonded on a circuit base member, which includes a circuit board, a circuit film and a circuit tape for subsequently placing the semiconductor devices in a cavity of the dies, so that a molten resin is injected into a cavity by a plunger of a molding machine to carry out a resin-encapsulation of the semiconductor devices.
Plural semiconductor devices are aligned in matrix over a single Circuit base member for subsequent resin-encapsulation thereof. It is possible in one method to encapsulate the single package semiconductor devices with resin sequentially. It is also possible in another method to encapsulate the plural packages semiconductor devices with resin at one time. The later method, for example, the batch resin encapsulation is superior in high productivity and lower cost.
The single semiconductor package resin-encapsulation method is a method in which the semiconductor devices for one package are resin-encapsulated in one cavity different from other cavity in which other semiconductor devices for other package are independently resin-encapsulated. Side faces of the encapsulating resin are defined by the inner shapes of the molding dies. Independent plural encapsulating resins for individual packages are formed by the resin-molding process in the molding dies. It is unnecessary to carry out a dicing process for cutting or dividing the encapsulating resin. If any interconnection layer or any solder-resist layer is present on the circuit base member or on its cutting line such as a scribe line, it is necessary to cut the interconnection layer or the solder-resist layer.
The batch resin-encapsulation method is a method in which the semiconductor devices for plural packages are resin-encapsulated in a single cavity at one time. In accordance with this batch resin-encapsulation method, the encapsulating resin encapsulating the semiconductor devices for the plural packages is formed in a single flat panel-shape unit, which is so called as a package panel. It is, therefore, necessary to divide the package panel into plural semiconductor packages by dicing process. Side faces of the individual semiconductor package are defined by cutting in the dicing process. The batch resin-encapsulation method for the transfer molding may be carried out either using a release film or without using any release film.
FIGS. 1A through 1D
are fragmentary cross sectional elevation views illustrative of top and bottom dies and plural semiconductor devices bonded on a circuit base member using the sequential steps involved in the conventional batch resin-encapsulation method for the transfer molding with a release film. Molding dies
120
comprise a top die
121
and a bottom die
122
. The top die
121
further comprises a top center block
24
. The bottom die
122
further comprises a bottom center block
25
and a circuit base member mounting block
142
. The bottom center block
25
is provided with a pot
27
which is to be filled with a resin
26
. In the pot
27
, the resin
26
is filled and further a plunger
28
is inserted for applying a pressure to the resin
26
. The top center block
24
is provided with a caliber
29
at a position corresponding to the pot
27
. Runners
30
as passages to a top cavity
23
for the molten resin
26
are formed in both sides of the caliber
29
. The top die
121
has the top cavity
23
a
which accommodates plural semiconductor devices
12
bonded on the circuit base member
111
, wherein the molten resin
26
is injected into the cavity
26
for encapsulating the semiconductor devices with the resin
26
. The runners
30
formed in both sides of the caliber
29
are connected with a first side of the cavity
23
a
adjacent to the top center block
24
. An air vent
146
is formed in a second side of the cavity
23
a
opposite to the first side. The air vent
146
relieves an inner gas in the cavity
23
a
upon injection of the molten resin into the cavity
23
a
. The air vent
146
comprises a channel groove formed in a cramp face of the top die
121
. The bottom die
122
has a bottom cavity
23
b
at a corresponding position to the top cavity
23
a
of the top die
121
. The bottom cavity
23
b
accommodates the circuit base member
111
. The top and bottom cavities
23
a
and
23
b
form a closed or sealed cavity for sealing the circuit base member
111
and the semiconductor devices
12
. The circuit base member
111
is mounted on the circuit base member mounting block
142
. The circuit base member mounting block
142
is depressed from a circumferential block to form the bottom cavity
23
b
for accommodating the circuit base member
111
. The circuit base member mounting block
142
is supported to be movable in up and down directions by a floating mechanism utilizing a spring member
43
. The movements in up and down directions of the circuit base member mounting block
142
cause variation in depth of the bottom cavity
23
b
. The floating mechanism is needed for a board type circuit base member which is variable in thickness. If the floating mechanism is not used, then the bottom cavity
23
b
is kept in depth. Notwithstanding, if the thickness-variable circuit board is mounted on the circuit base member mounting block
142
, this means that the surface level of the thickness-variable circuit board is thus variable. If the thickness of the circuit board mounted on the bottom cavity
23
b
is too thick relative to the fixed depth of the bottom cavity
23
b
, then an excess cramping pressure is applied to the board, whereby the board receives a damage. If the thickness of the circuit board mounted on the bottom cavity
23
b
is too thin relative to the fixed depth of the bottom cavity
23
b
, then an insufficient cramping pressure is applied to the board and a gap is formed, whereby a leakage of the molten resin from the gap appears. The floating mechanism is provided to solve the above problems caused by the variation in thickness of the circuit board. If the tape type circuit base member
111
is used, then the floating mechanism is not needed because the tape type circuit base member
111
is thin and variation in thickness of the tape type circuit base member ill is so small and causes no problem.
The top die
121
has an adsorption hole
44
for vacuum-adsorbing a release film. The adsorption hole
44
has an opening
44
a
adjacent to the top cavity
23
a.
The adsorption hole
44
provides a connection between the top cavity
23
a
and a non-illustrated external vacuum source. If no release film is needed or the dies, then it is unnecessary to provide the adsorption hole
44
.
The resin molding machine not illustrated is provided with the dies
120
. The resin molding machine further has a top base not illustrated for supporting the top die
121
and a bottom base not illustrated for supporting the bottom die
122
as well as has a heater not illustrated for heating the dies
120
, a vacuum pump not illustrated and serving as a vacuum source and a cramping mechanism not illustrated and further an injection mechanism not illustrated. The resin molding machine further more has a plunger
28
. The top and bottom dies
121
and
122
are fixed to the top and bottom bases by plates or volts respectively. The top base or the bottom base is elevated for closing motions of the dies
120
.
The conventional batch resin molding method for molding the semiconductor devices and the method of forming the semiconductor devices will be described.
[Bonding Process]
A bonding process occurs prior to the resin-
Shimizu Kazuo
Tsuruta Hisayuki
Hayes & Soloway P.C.
NEC Electronics Corporation
Ortiz Angela
LandOfFree
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