Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-01-27
2001-05-08
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S762010
Reexamination Certificate
active
06229321
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for manufacturing a high frequency multichip module that includes a high frequency bare chip mounted on a substrate. The bare chip has a ground electrode disposed at the opposite side to the signal electrodes. More particularly, the present invention relates to a process for manufacturing a high frequency multichip module, which can omit a performance test of the small-sized high frequency bare chip after mounting the bare chip and other components on the substrate.
Conventionally, such a bare chip used for manufacturing a high frequency multichip module is mounted on a substrate
1010
as shown in a top view of FIG.
1
. On the substrate
1010
, signal electrodes
1011
and ground electrodes
1012
are arranged alternately on the same plane. The coplanar type bare chip
1020
also has signal electrodes
1021
and ground electrodes
1022
arranged alternately on the same plane of the coplanar type bare chip
1020
, corresponding to the signal electrodes
1011
and ground electrodes
1012
. Each of the signal electrodes
1021
and ground electrodes
1022
is connected to the corresponding signal electrode
1011
or ground electrode
1012
by bonding wire
1030
.
In order to measure high frequency characteristics of such a coplanar-type bare chip
1020
by a coplanar-type probe
1000
, it was a precondition that the signal electrodes
1021
and the ground electrodes
1022
of the coplanar-type bare chip
1020
are arranged on the same plane as illustrated. And the coplanar type probe
1000
has a center conductor tip portion
1001
that is pressed to the signal electrode
1021
and ground conductor tip portions
1002
that are pressed to the ground electrodes
1022
. Therefore, the center conductor tip portion
1001
and the ground conductor tip portions
1002
should be arranged on the same plane that is perpendicular to the pressing direction, and as the coplanar-type bare chip
1020
.
As illustrated in
FIG. 2
, a horizontal-type probe or the coplanar-type probe
1110
has conductor tip portions horizontally arranged. The conductor tip portions are a center conductor tip portion
1111
having a flat spring shape and ground conductor tip portions
1112
disposed at the both sides of the center conductor tip portion
1111
. And these conductor tip portions
1111
and
1112
are arranged on the same plane. Therefore, the center conductor tip portion
1111
and the ground conductor tip portions
1112
are pressed to the signal electrode
1121
and the ground electrodes
1122
of the coplanar type bare chip
1120
to make electrical contact between each of the conductor tip portions and the corresponding electrode.
As described above, since the coplanar type bare chip
1120
has a signal electrode
1121
and ground electrodes
1122
arranged at both sides of the signal electrode
1121
on the same plane, the area of the coplanar type bare chip
1120
becomes large. For example, if the area of a GaAs-MMIC (monolithic microwave integrated circuit) is large, the number of bare chips that can be made from an expensive GaAs wafer becomes small, so that the cost per chip rises.
When using a peripheral electrode arrangement such as a grid electrode arrangement with bump connection, high cost is still a problem in the same way as described above.
Recently, in order to solve the above-described problem and to obtain a smaller area of the electrodes for external connection capable for high-density mounting, a microstrip-type bare chip is being used. The microstrip-type bare chip has a ground plane on the rear side so as to reduce the ground electrodes on the front side.
However, as illustrated in
FIGS. 3A and 3B
, using the above-described coplanar type probe
1210
, it is difficult to measure the high frequency characteristics of the microstrip-type bare chip
62
, because the microstrip-type bare chip
62
has a signal electrode
62
-
1
only but no ground electrode on the front surface to be contacted with the ground conductor tip portion
1212
of the coplanar type probe
1210
. Instead the microstrip-type bare chip
62
has a ground plane
62
-
2
at the rear side. As the result, the coplanar type probe
1210
does not contact any ground level when the center conductor tip portion
1211
contacts the signal electrode
62
-
1
on the front surface of the microstrip type bare chip
62
.
In order to solve the above-described problem, a quad flat package (QFP) is realized, which has a peripheral electrode arrangement as shown in
FIGS. 4A and 4B
. In this arrangement, inner electrodes are lead out to the periphery of the chip and arranged flatly. This peripheral electrode arrangement enables measurement with the coplanar-type probe
1312
by arranging the signal electrodes and the ground electrodes alternately on outer-substrate electrodes
1322
via inner-substrate electrodes
1321
. On the other hand, measurement with the coplanar-type probe
1311
is not possible since the microstrip type bare chip
1330
mounted on the substrate
1320
has a rear ground plane.
Therefore, as illustrated in
FIG. 5
, the manufacturing process of the high frequency multichip module illustrated in
FIGS. 4A and 4B
is realized. At first, a preprocess (step
1401
) is performed as a step of component mounting (step
1402
) in which the microstrip-type bare chip
1330
and other components are mounted on the substrate
1320
, and wire bonding is performed with metal wires
1340
. After this step, the coplanar-type probe
1312
is used for the outer-substrate electrodes
1322
so as to measure the high frequency characteristics and to test the performance in a step of a performance test (step
1403
). If the mounted component performs well in the performance test (“GOOD” in step
1403
), a shipment/manufacture step (step
1404
) is performed next in which the product is shipped or the next manufacture step is performed to finish the process (End #1).
If the mounted component is “NG” in the performance test of the above step
1403
, it is checked if the mounted component can be replaced with new one in a step of “replaceable” (step
1405
). If the replacement is possible by “YES” of step
1405
, the mounted component is replaced with a new one in a step of replacing (step
1406
) and the process returns to the above-described step
1402
so as to mount and test the performance of the new mounted component.
If the replacement is impossible, in other words, the result of the step
1405
is “NO”, this defective product is rejected in the rejection step (step
1407
) and the process finishes (End #2).
However, the above-described conventional process for manufacturing the high frequency multichip module has the following problem. Since the conventional probe is coplanar-type, it is difficult to measure the high frequency characteristics of the single bare chip before mounting. Therefore, the performance test of the microstrip-type bare chip should be performed after the mounting of components. In addition, if the result of the performance test is “NG”, the defective product should be replaced with a new one. This replacement should be repeated until the result of the performance test is “GOOD”, so that the manufacturing time and costs are increased.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described problems. The present invention provides a process for manufacturing a high frequency multichip module which can reduce the manufacturing time and cost by measuring the high frequency characteristics of a single bare chip before mounting. And this single bare chip is compact and is a rear ground chip such as microstrip-type bare chip with a rear ground plane.
In order to attain this object, the measurement of the high frequency characteristics of the high frequency multichip module is performed using a vertical-type probe in the manufacturing process of the present invention. The vertical-type probe has a center conductor and ground conductors arranged at both sides of the center conductor in the ve
Hayakawa Satoshi
Inoue Hirobumi
Matsunaga Kouji
Nikaidou Masahiko
Tanehashi Masao
Metjahic Safet
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Tang Minh
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