Semiconductor module

Details Semiconductor module Semiconductor module

2000-07-20

2002-04-30

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C165S086000, C165S185000, C174S016300, C257S713000, C257S719000, C361S710000, C361S719000

Reexamination Certificate

active

06381137

ABSTRACT:

BACKGROUND OF THE INVENTION
1.) Technical Field of the Invention
The present invention relates to a semiconductor module incorporating a heat-spreader dissipating heat produced by a semiconductor memory device mounted thereon.
2.) Description of Related Arts
A semiconductor module comprises a plurality of components such as the semiconductor memory device, each of which should be kept at or under a predetermined tolerable operation temperature so that each component can operate to function appropriately.
Especially, since the memory device such as Rambus DRAM running at a high transfer rate, produces enormous heat during the operation, the package of the semiconductor module substantially heats up. Without dissipating heat, the semiconductor module may overheat to malfunction. Therefore, it is critical to maintain the temperature of each component of the semiconductor module less than the predetermined tolerable operation temperature.
In general, a heat-spreader (a heat dissipating plate) is applied for dissipating the heat produced by the semiconductor components mounted on the circuit board, for example, the memory devices so as to prevent the semiconductor module from malfunctioning. The heat-spreader is disposed in contact as widely as possible with each of such semiconductor components to maximize the heat dissipating effect.
Meanwhile, the semiconductor module includes a plurality of semiconductor components, each of which has a height from the surface of the circuit board to the top surface thereof. The height of the semiconductor component is referred to as a “mounting height” hereinafter. The mounting heights of the semiconductor components have deviated from one another, for example, due to the mounting conditions of the semiconductor components. Therefore, in case where the heat-spreader used for the heat dissipating plate is disposed upon the semiconductor components mounted on the circuit board, the semiconductor component having the shorter mounting height cannot reach to and contact with the heat-spreader with a gap therebetween.
As described above, the semiconductor component spaced from the heat-spreader may overheat to malfunction without dissipating heat through the heat-spreader.
In order to solve the problem due to the uneveness of the mounting heights, a conventional semiconductor module takes an approach to dissipate heat produced by the semiconductor components by interposing a thermal sheet with a high thermal conductivity between the heat-spreader and the semiconductor components.
Referring to
FIGS. 8A and 8B
, the conventional semiconductor module dissipating heat through the thermal sheet and the heat-spreader will be described in detail hereinafter.
FIG. 8A
is a schematic top view of the conventional semiconductor module, and
FIG. 8B
is a cross sectional view taken along a line VIIIB—VIIIB in FIG.
8
A. As shown in the drawings, the conventional semiconductor module
101
comprises, in general, a circuit board
102
made of material such as epoxy resin and circuit patterns printed thereon (not shown).
The conventional semiconductor module
101
further comprises a plurality of semiconductor components
103
(for example, memory devices
103
a
,
103
b
,
103
c
,
103
d
), which are mounted on the circuit board
102
and connected with the aforementioned circuit patterns, and a heat-spreader
104
made of material such as metal or alloy of aluminum with a comparatively high thermal conductivity. When the heat-spreader
104
is disposed on the semiconductor components
103
, as the mounting heights of the semiconductor components
103
are not even, all of the semiconductor components
103
are not always in contact with the heat-spreader
104
, and the semiconductor components
103
with shorter mounting heights are spaced away from the heat-spreader
104
with a gap.
To address this problem, the conventional semiconductor module fills this gap between the semiconductor components
103
and the heat-spreader
104
with the thermal sheet
105
made of material such as resin with a high thermal conductivity. This thermal sheet
105
is made of resin with some flexibility, so that when the heat-spreader
104
presses the thermal sheet
105
against the semiconductor components
103
, the thermal sheet
105
can closely contact with both the semiconductor components
103
and the heat-spreader
104
. Thus, the conventional semiconductor module
101
can dissipate heat produced by the semiconductor components
103
through the thermal sheet
105
and the heat-spreader
104
. As shown in
FIG. 8B
, the heat-spreader
104
includes a pair of opposing end portions which are bent downwardly to provide a portion for securing the heat-spreader
104
onto the circuit board
102
with a securing member
106
such as rivets.
As described above, the conventional semiconductor module
101
is comprised such that heat generated by the semiconductor components
103
is diffused through the thermal sheet
105
, which closely contacts with the semiconductor components
103
and the heat-spreader
104
.
However, since the thermal sheet
105
is generally made of resin, it has a thermal conductivity substantially less than that of aluminum metal. This causes heat produced by the semiconductor components
103
to prevent from being diffused enough to the heat-spreader
104
. Eventually, this leads the semiconductor components
103
overheated to malfunction when the semiconductor components
103
cannot be kept at or under the predetermined tolerable operation temperature.
To address this problem, an another conventional semiconductor module
101
disclosed in JPA 11-15566, incorporates a thermal sheet
105
(a flexible thermally conductive member) which has a great flexibility and a high thermal conductivity so that the thermal sheet
105
can more closely contact with the heat-spreader
104
and semiconductor components
103
to sufficiently diffuse heat. Yet, this approach raises a problem that the such a thermal sheet
105
having a great flexibility and a high thermal conductivity are made of material such as porous graphite material and multi-metal-film layered material which are quite difficult and expensive to manufacture.
SUMMARY OF THE INVENTION
The present invention is addressed to those aforementioned problem, the object of the present invention is to provide a semiconductor module which can effectively dissipate heat generated by the semiconductor components disposed on the circuit board, with a simple structure to manufacture inexpensively.
The semiconductor module according to first aspect of the present invention comprises: a circuit board; a plurality of semiconductor components mounted in a matrix (m lines by n rows, m and n are natural numbers) on the circuit board; and a plurality of heat-spreaders arranged in a matrix (m lines by n rows), each of said heat-spreaders closely contacting each of said semiconductor components; wherein the first line and m-th line of said heat-spreaders are bonded onto said circuit board, and wherein said heat-spreaders at least in lines are bonded to adjacent ones. Thus, even where the mounting heights of the semiconductor components are deviated one another, since each of the heat-spreaders is individually assembled onto the circuit board in a simple manner, to closely contact with the semiconductor components. Therefore, the semiconductor module of the present invention can effectively dissipate heat generated by the semiconductor components directly through the heat-spreaders with a simple structure to manufacture inexpensively.
According to the semiconductor module of the present invention, the natural number n is 1, and m pieces of the heat-spreaders are arranged in a line, and wherein m pieces of the heat-spreaders are bonded to adjacent ones.
According to the semiconductor module of the present invention, each of the heat-spreaders has a step portion with a predetermined height, and wherein the heights of the heat-spreaders is greater than those of the semiconductor components and shorter than those of the th

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