Method of making hybrid integrated circuit device

Details Method of making hybrid integrated circuit device Method of making hybrid integrated circuit device

2002-06-27

2003-07-15

Chaudhari, Chandra (Department: 2813)

Semiconductor device manufacturing: process

Packaging or treatment of packaged semiconductor

Making plural separate devices

C438S124000, C438S127000

Reexamination Certificate

active

06593169

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method of, and more particularly to a manufacturing method of hybrid integrated circuit device having a resin seal body formed on a hybrid integrated circuit substrate by transfer molding.
Generally, there are, principally, two methods of sealing employed for hybrid integrated circuit devices.
The first method employs member having such a form as placing a lid, generally called a case member, on a hybrid integrated circuit substrate mounted with circuit elements of semiconductor chips or the like. This structure includes a hollow structure or that having a resin separately filled therein.
The second method is injection molding as a process to mold semiconductor ICs. This is described, e.g. in Japanese Patent Publication No. H11-330317. The injection molding generally uses thermoplastic resin. For example, the resin heated at 300° C. is injected under a high injection pressure and poured into a mold at one time, whereby the resin is molded. Since a resin polymerization time is not required after pouring a resin into a mold, there is a merit to shorten the operation time as compared with transfer molding.
Explanation will be made on a method of manufacturing a conventional hybrid integrated circuit device using injection molding, with reference to
FIGS. 9
to
12
C.
First, an aluminum (hereinafter, referred to as Al) substrate
1
is employed as a metal substrate as shown in
FIG. 9
, in order for explanation.
The Al substrate
1
is anodized in its surface. Furthermore, a resin
2
having an excellent insulation property is formed on the entire surface of the anodized Al substrate
1
. However, the oxide may be omitted where voltage resistance is not taken into consideration.
As shown in
FIGS. 12B and 12C
, a resin seal body
10
is formed by a support member
10
a
and a thermoplastic resin. Namely, a substrate
1
mounted on the support member
10
a
is covered with thermoplastic resin by injection molding. The support member
10
a
and the thermoplastic resin have an abutment region. The abutment region of support member
10
a
is fused by the poured hot thermoplastic resin, thereby realizing a full-mold structure as shown in FIG.
10
.
Herein, the thermoplastic resin adopted is a resin called PPS (polyphenyl sulfide).
The injection temperature of thermoplastic resin is as high as 300° C. Consequently, there is a problem that solder
12
be fused by the hot resin thereby causing poor soldering. For this reason, an overcoat
9
is formed by potting a thermosetting resin (e.g. epoxy resin) in a manner previously covering solder joints, metal fine wires
7
, active elements
5
and passive elements
6
. Due to this, the fine wires (approximately 30-80 &mgr;m) particularly are prevented from being fallen down and broken under an injection resin pressure during forming with a thermoplastic resin.
The resin seal body
10
is formed through two stages shown in
FIGS. 12B and 12C
. In the first stage, a gap is provided at between a backside of the substrate
1
and a mold die. The support member
10
a
is placed on the backside of the substrate, in consideration of securing a thickness at a backside of the substrate
1
upon poring a resin under a high pressure into the gap. In the second stage, the substrate
1
mounted on the support member
10
a
is covered with a thermoplastic resin by injection molding. In the abutment region between the support member
10
a
and the thermoplastic resin, the abutment region of the support member
10
a
is fused by the poured hot thermoplastic resin thereby realizing a full-mold structure. Herein, the thermoplastic resin on the support member
10
a
preferably has an equivalent thermal expansion to that of the substrate
1
.
Next, explanation will be made on a conventional method of manufacturing a hybrid integrated circuit device using injection molding, with reference to
FIGS. 10
to
12
C.
FIG. 10
is a flowchart, including a metal substrate preparing process, an insulating layer forming process, a Cu foil pressure-laying process, a partial Ni plating process, a Cu foil etching process, a die bonding process, a wire bonding process, a potting process, a lead connection process, a support member attaching process, an injection mold process and a lead cutting process.
FIGS. 11A
to
12
C show the sectional views of the processes. Note that the processes, that are apparent without showing, are omittedly shown.
At first,
FIGS. 11A and 11B
show a metal substrate preparing process, an insulating layer forming process, a Cu foil pressure-laying process, a partial Ni plating process and a Cu foil etching process.
In the metal substrate preparing process, prepared is a substrate in consideration of its property of heat dissipation, substrate strength, substrate shield and the like. This example uses an Al substrate
1
having a thickness, e.g. of approximately 1.5 mm, excellent in heat dissipation property.
Next, a resin
2
excellent in insulation property is further formed over the entire surface of the aluminum substrate
1
. On the insulating resin
2
, a Cu conductor foil
3
is pressure-laid to constitute a hybrid integrated circuit. On the Cu foil
3
, an Ni plating
4
is provided over the entire surface in consideration of adhesion to a metal fine wire
7
electrically connecting between the Cu foil
3
as a lead-out electrode and an active element
5
.
Thereafter, a known screen-printing is used to form Ni plating
4
a
and a conductive path
3
a.
Next,
FIG. 11C
shows a die bonding process and a wire bonding process.
On the conductive path
3
a
formed in the preceding process, an active element
5
and a passive element
6
are mounted through a conductive paste such as a solder paste
12
, thereby realizing a predetermined circuit.
Next,
FIGS. 12A and 12B
show a potting process, a lead connection process and a support member attaching process.
As shown in
FIG. 12A
, in the potting process, prior to a later injection mold process, potting is previously made with a thermosetting resin (e.g. epoxy resin) onto the solder junctions, metal fine wires
7
, active elements
5
and passive elements
6
, thereby forming an overcoat
9
.
Next, prepared is an outer lead
8
for outputting and inputting signals from and to the hybrid integrated circuit. Thereafter, the outer lead
8
is connected to the external connection terminal
11
formed in a peripheral area of the substrate
1
through a solder
12
.
Next, as shown in
FIG. 12B
, the hybrid integrated circuit substrate
1
connected with the outer lead
8
and the like is mounted on a support member
10
a
. By mounting the substrate
1
on the support member
10
a
, it is possible to secure a thickness of a resin seal body at a backside of the substrate
1
during injection molding as explained in the next process.
Next,
FIG. 12C
shows an injection mold process and a lead cutting process.
As shown in the figure, after potting is done with a thermosetting resin on the substrate
1
to form a overcoat
9
, a resin seal body
10
is formed by injection molding. At this time, in the abutment region between the support member
10
a
and the thermoplastic resin, the abutment region of the support member
10
a
is fused by the injected hot thermoplastic resin and turned into a full-mold structured resin seal body
10
.
Finally, the outer lead
8
is cut to a use purpose thereby adjusting the length of the outer lead
8
.
By the above process, a hybrid integrated circuit device is completed as shown in FIG.
9
.
On the other hand, in the semiconductor industry, it is a general practice to carry out a transfer mold process. In a hybrid integrated circuit device by the conventional transfer molding, a semiconductor chip is fixed on a leadframe, e.g. of Cu. The semiconductor chip and the lead are electrically connected through a gold wire (hereinafter, referred to as Au). This is because the impossibility of employing an Al fine wire in respect of ready bendability and time-consumed bonding requiring ultrasonic waves

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