Apparatus for manufacturing semiconductor packages

Details Apparatus for manufacturing semiconductor packages Apparatus for manufacturing semiconductor packages

2000-10-13

2003-09-09

Davis, Robert (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

Distinct means to feed, support or manipulate preform stock...

Opposed registering coacting female molds

C425S125000, C425S544000, C425S572000, C425S588000, C425S444000

Reexamination Certificate

active

06616436

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of and apparatus for manufacturing semiconductor packages, and more particularly, but not by way of limitation, to a mold assembly for manufacturing semiconductor packages which allows leadframes to be easily separated from a top mold section after a molding process.
2. History of Related Art
It is conventional in the electronic industry to encapsulate one or more semiconductor devices, such as integrated circuit chips, in a semiconductor package. These plastic packages protect a chip from environmental hazards, and provide means for electrically and mechanically attaching the chip to an intended device. Recently, such semiconductor packages have included metal leadframes for supporting an integrated circuit die which is bonded to a chip paddle region thereof Bond wires which electrically connect pads on the integrated circuit die to individual leads of the leadframe are then incorporated. A hard plastic encapsulant material which covers the bond wire, the integrated circuit die and other components, forms the exterior of the package. A primary focus in this design is to provide the die with adequate protection from the external environment in a reliable and effective manner.
As set forth above, the semiconductor package therein described incorporates a leadframe as the central supporting structure of such a package. A portion of the leadframe completely surrounded by the plastic encapsulant is internal to the package. Portions of the leadframe extend internally from the package and are used to connect the package externally. More information relative to leadframe technology may be found in Chapter 8 of the book
Micro Electronics Packaging Handbook
, (1989), edited by R. Tummula and E. Rymaszewski. This book is published by Van Nostrand Reinhold, 115 Fifth Avenue, New York, N.Y.
Once the integrated circuit dies or chips have been produced and encapsulated in a semiconductor package described above, they may be used in a variety of electronic appliances. A wide variety of electronic devices have been developed in recent years, such as cellular phones, portable computers, etc. Each of these devices typically includes a motherboard on which a significant number of such semiconductor packages are secured to, provide multiple electronic functions. These electronic appliances are themselves required to be reduced in size as consumer demand increases. Accordingly, not only are semiconductor chips highly integrated, but also semiconductor packages are miniaturized with a high increase of package mounting density.
According to such miniaturization tendency, semiconductor packages, which transmit electrical signals from semiconductor chips to motherboards and support the semiconductor chips on the motherboards, have been designed to have a size of about 1×1 mm to 10×10 mm.
Aspects of the above-referenced manufacturing steps are set forth and shown in
FIGS. 1 and 2
, which are now referenced in combination. During the encapsulating step for constructing the semiconductor package as shown in
FIG. 1
, a plate-configuration bottom mold
10
is constructed with housing parts
12
. The housing parts
12
are sunken to a predetermined depth from the upper surface
13
of the bottom mold
10
so as to allow the leadframe
30
(shown in
FIG. 2
) to be firmly placed thereon during encapsulation. The housing parts
12
are provided with a plurality of fixing pins
14
which are inserted into and fix the guide pinholes
29
formed in the leadframe
30
(shown in FIG.
2
).
Still referring to
FIG. 1
, a top mold
20
is shown above bottom mold
10
. The top mold
20
is also of a plate configuration, having a plurality of transports
22
which perforate the top mold
20
in the vertical direction. In the top mold
20
, a runner
24
is grooved to a depth with a connection to each of the transports
22
. Forming a tree-like configuration, a plurality of gates
26
are also grooved to a depth with connections to the runner
24
. At the terminus of each of the gates
26
is formed a cavity
28
in which the package body
32
of the semiconductor package will be formed, as described in more detail below.
In operation, the bottom mold
10
and top mold
20
are used to encapsulate an assembled leadframe
30
placed therebetween. First, the leadframe
30
is safely placed on the housing parts
12
of the bottom mold
10
. At this time, the guide pinholes
29
formed in the leadframe
30
are engaged with the fixing pins
14
formed in housing parts
12
to accurately fix the leadframe
30
(shown in FIG.
2
). The top mold
20
is then clamped to the bottom mold
10
. An amount of an encapsulation material is then introduced into the transports and pressurized with a transfer ram (not shown) to flow the encapsulation material through the runners
24
and the gates
26
into the cavities
28
, described above.
Referring now to
FIG. 2
, following the filling of the encapsulation material between the bottom mold
10
and top mold
20
housing the leadframe
30
, the top mold
20
is taken off, after which the leadframe
30
is removed out of the bottom mold
10
and subjected to the next process. In
FIG. 2
, there is shown the leadframe
30
after the encapsulation is completed on the bottom mold
10
. It is conventional in the art to maintain the top mold
20
and the bottom mold
10
at such a predetermined temperature that the encapsulation material can smoothly flow through the runners
24
and the gates
26
to the cavities
28
. After completion of the encapsulation, dregs of the encapsulation material which remain on the bottom mold
10
and the leadframe
30
, that is, a transport curl
42
, a runner curl
44
and a gate curl
46
are all removed.
After completion of the encapsulation, when the top mold is separated from the bottom mold, the leadframe frequently remains adhered to the top mold on account of the high adhesiveness of the encapsulation material. It is at this point that forcible secession by the hand of an operator can cause the breakage or bending of the leadframe. This aspect of the production process is a distinct disadvantage and is addressed by the present invention.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a method of and apparatus for manufacturing semiconductor packages. More particularly, one aspect of the present invention includes a mold for manufacturing semiconductor packages, which allows leadframes to be easily separated from its top mold after a molding process. In another aspect, the present invention includes a mold for manufacturing semiconductor packages comprising a bottom mold having housing parts on the upper surface so as to allow leadframes to be placed in a flat state therein, and a top mold comprising transports perforating through the top mold in the vertical direction; runners formed at its lower surface with connections to the transports so as to introduce an encapsulation material into targets; a plurality of gates connected to the runner; and a volume of a cavity at the terminus of each of the gates, in which a package body is to be formed. A plurality of eject pins are mounted in the top mold for reciprocating into and out of the runners, thereby easily separating the leadframes from the top mold when the pins are actuated and move into the runners.
In a further aspect of the present invention, the above described invention includes eject pins formed at the intersections between the runners and the gates. Moreover, in the mold of the present invention, the runner curl which is most strongly stuck to the top mold can be pushed out downwardly by use of the eject pins so as to easily separate the leadframe from the top mold.
In yet another aspect of the present invention, a method of manufacturing a packaged semiconductor is presented. The method of making the packaged semiconductor includes the steps of providing a mold for manufacturing a packaged semiconductor upon a leadframe. The leadframe is of the type having a ch

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