Lead structure of semiconductor device

Disclosed is a semiconductor device such as a DIP (Dual In-line Package) or PGA (Pin Grid Alley), which has a plurality of leads protruding only from one surface of a flat package. A single independent lead protrudes from the surface of the package at the position which is aligned with a guide hole formed in the package. The independent lead has a bore which penetrates through the lead lengthwise and connects to the guide hole. A wiring member of an electronic part or the like placed in the bore via the guide hole is soldered to the inner wall of the independent terminal.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a semiconductor device, and, more 
particularly, to a semiconductor device having leads protruding from only 
one surface of a flat package, such as a PGA (Pin Grid Alley) or DIP (Dual 
In-line Package). 
2. Description of the Related Art 
Semiconductor devices of the PGA and DIP types have leads arranged along 
only one surface of the package, making their mount on printed circuit 
boards easier, and are thus popular today. To make the package of this 
type of semiconductor device smaller, a plurality of leads 103 are 
arranged close to one another on the bottom of the package 101, as shown 
in FIG. 6. The leads 103 are inserted in holes in a printed circuit board 
(PCB) 120 and are soldered to the printed circuit. Thereafter, the leads 
of other electronic parts or the like are soldered to the printed circuit. 
As the number of the leads 103 of the device increases, the number of 
printed circuits increases accordingly, increasing the area of the PCB 
120. This naturally requires greater space to accommodate the PCB 120, 
enlarging the general PCB assembly. 
The semiconductor device disclosed in Japanese unexamined utility Model 
Publication No. 23087/1987 has an IC socket situated between a PCB and the 
semiconductor device. This IC socket has leads for connection to the PCB 
and leads for connection to other electronic parts. This design requires 
no intervention of the PCB to connect a PGA to the other electronic parts. 
In this case too, the PCB assembly is enlarged by the space of the IC 
socket. 
SUMMARY OF THE INVENTION 
It is therefore a primary object of the present invention to provide a 
semiconductor device which has leads protruding from only one surface, 
such as a DIP or a PGA, and can ensure a compact assembly when connected 
to other electronic parts. 
It is another object of this invention to provide a semiconductor device 
which is firmly connectable to the leads of other electronic parts or the 
like. 
To achieve the foregoing and other objects, the present invention is 
directed to a lead structure of a semiconductor device to which a wiring 
member of an electronic part is to be connected, the lead structure 
comprising in a flat semiconductor package; a through hole formed in the 
semiconductor package: and a lead electrode protruding from the 
semiconductor package at a position aligned with the through hole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, a cavity 2 is formed on the top of a PGA type ceramic package 1. 
A semiconductor device 6 is adhered via a connect layer 5 to the bottom of 
the cavity 2. A plurality of lead pins 3 protruding from the bottom of the 
package 1 are connected to a lead frame, i.e., a printed circuit (not 
shown) provided in the package 1. An end portion exposed in the cavity 2 
is connected to the semiconductor device 6 by bonding wires 7. A cap 9 is 
adhered by seal member 8, such as Ag-paste or solder, to the top of the 
package 1 in association with the cavity 2, shielding the cavity 2. 
A through hole 11 is formed in that portion of the package 1 which is 
spaced apart from the cavity 2. The cap 9 has a size to cover only the 
cavity 2, and the through hole 11 is located outside the cap 9. A metal 
cylindrical lead connector 12 is brazed with a brazing filler metal 4 to 
the bottom of the package 1 at the position corresponding to the through 
hole 11. The lead connector 12, like the lead pins 3, is connected via a 
lead to the semiconductor device 6. 
A flange is formed at the upper end portion of the lead connector 12 so 
that the adhesive area to the package is large. The lead connector 12 has 
a bore 12a having the same diameter as the through hole 11 of the package 
1. The brazing filler metal 4 for coupling the lead connector 12 to the 
package 1 has a hole bored through, which has the same diameter as the 
bore 12a and the through hole 11. Accordingly, the through hole 11 and the 
bore 12a are connected vertically. The lead connector 12 is formed shorter 
than the lead pins 3. 
As shown in FIG. 2, the individual lead pins 3 are inserted in bores 21a 
formed in a printed circuit board 21 and are securely connected thereto by 
solder 22. As shown, the lead connector 12 will not contact the printed 
circuit board 21. 
A wiring member 23 is inserted into the through hole 11 and the bore 12a 
from the upper surface of the package 1, and is brazed to the inner wall 
of the bore 12a. The wiring member 23 is therefore connected to the 
semiconductor device 6 via the lead connector 12. This can eliminate the 
need for a structure which connects the wiring member via the printed 
circuit board 21 to the semiconductor device 6. 
According to this embodiment, the material of the package 1 is alumina, PZT 
(essentially consisting of lead, zirconium and titanium), mullite, alumina 
nitride or the like. The material for the connect layer 5 and seal member 
8 is a brazing filler metal, such as an Ag paste or solder, or an epoxy 
resin. 
Since the wiring member 23 is first inserted in the through hole 11 and the 
bore 12a and is then connected to the inner wall of the bore 12a by 
brazing, the attachment is firmer as compared with the case where brazing 
is made on the outer surface of the lead connector 12. Even with external 
force applied to the wiring member 23, therefore, the wiring member 23 is 
prevented from being separated from the lead connector 12. The wiring 
member 23 may be replaced with a lead of another electronic part. 
According to this embodiment, wiring is accomplished on the top and bottom 
of the package 1 via the lead connector 12 and the lead pins 3. The wiring 
efficiency therefore increases while reducing the wiring space. 
A second embodiment of this invention will now be described referring to 
FIG. 3. 
In this embodiment, the through hole 11 in the package 1 is formed larger 
than the bore 12a of the lead 12, and a funnel portion 12b is formed at 
the upper end portion of the bore 12a. The upper edge of the funnel 
portion 12b has the same diameter as the through hole 11. 
With the above structure, even if the relative position of the bore 12a to 
the through hole 11 is slightly shifted, sufficient connection between the 
through hole 11 and the bore 12a is still assured. At the time of 
attaching the lead 12 to the package 1, therefore, the accuracy of the 
relative position of both through hole 11 and bore 12a does not matter so 
much, resulting in simpler manufacturing procedures. 
Further, with the through hole 11 and the bore 12a precisely aligned with 
each other, the wiring member 23 or another lead inserted through the 
larger-diameter through hole 11 smoothly reaches inside the bore 12a along 
the tapered inner wall of the funnel portion 12b. This facilitates the 
attachment of the wiring member 23. 
FIG. 4 illustrates a third embodiment of this invention. 
In this embodiment, the lead 12 has the same length as the lead pins 3. The 
lower end portion of the lead 12 has a diameter equal to that of the lead 
pins 3. The lead 12, like the lead pins 3, is inserted in the associated 
bore 21a in the printed circuit board 21 and is firmly soldered to the 
inner wall of the respective bore 21a. 
This structure permits the lead 12 to contact both the printed circuitry on 
the printed circuit board 21 in addition to the wiring of the wiring 
member 23 from the top of the package 1 as in the first embodiment. This 
further improves the wiring efficiency. 
As the cylindrical lead 12 as well as the lead pins 3 are brazed to the 
printed circuit board 21, the package 1 is firmly secured to the board 21. 
FIG. 5 illustrates a fourth embodiment of this invention. 
In this embodiment, the lead 12 is inserted into the through hole 11 in the 
package 1 and is brazed to the inner wall of the hole 11. This structure 
allows the lead 12 to be securely attached to the package 1, preventing 
the lead 12 from easily being separated from the package 1. Although not 
shown in the diagram, the lead 12 may be provided with a flange as in the 
previously described embodiments. In this case, if the bottom of the 
flange is brazed to the top of the package 1, the separation of the lead 
12 from the package 1 is prevented more effectively. 
Although only four embodiments of the present invention have been described 
herein, it should be apparent to those skilled in the art that the present 
invention may be embodied in many other specific forms without departing 
from the spirit or scope of the invention. 
Therefore, the present examples and embodiments are to be considered as 
illustrative and not restrictive and the invention is not to be limited to 
the details given herein, but may be modified within the scope of the 
appended claims. For example, the lead 12 may be attached to the bottom of 
the package 1. The lead 12 may have other proper shapes than a cylindrical 
shape, such as a C-shaped cross-section. The package 1 may be made of 
other materials than ceramic, such as metal and epoxy resin. The package 1 
may be adapted for a PGA having a face-down structure instead of a face-up 
structure. In addition, this invention may be applied to semiconductor 
devices of other types than the PGA type, such as a DIP and QIP (Quarrel 
In-line Package), which have leads protruding from only one surface and 
being oriented in one direction.