JPH05102359A - Colling structure for memory module - Google Patents

Abstract

PURPOSE:To provide a cooling structure of a memory module, which has mounted a plurality of semiconductor storage elements on a substrate, preventing malfunction of a semiconductor storage element due to overheating and ensuring stable operation thereof by eliminating heat generated during operation from the semiconductor storage element. CONSTITUTION:A polyimide film 3 is extended over a memory module mounting a semiconductor storage element package 1 and the inside of the polyimide film 3 is filled with a cooling agent 4 and the circumference thereof is sealed with a sealing area 6. Thereby, since heat generated from a semiconductor storage element package during operation of the memory module can be eliminated effectively, the memory module mounted in high density can be utilized. Moreover, such memory module provides an effect that reduction of thickness and weight of the casing can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory module, and more particularly to a cooling structure for removing heat generated during operation.

[0002]

2. Description of the Related Art A memory module has a plurality of semiconductor memory elements arranged in close proximity on a printed wiring board having a circuit pattern formed thereon and is used as an extended memory device for personal computers and workstations. As a method of cooling this memory module, a semiconductor memory element is mounted on a flexible substrate and folded in two to surround a foam rubber mat. A method of inserting it into a metal housing and allowing the semiconductor memory element to sufficiently contact the metal housing with the elastic force of the foamed rubber mat to cool it is disclosed by IBM Technology Disclosure Bulletin, 27, (19).
84) p. 2642 (IBM Technology)
Disclosure Bulletin, Vol. Two
7, No. 4B, (1984) pp. 2642).

[0003]

However, in the above-mentioned prior art, when a plurality of semiconductor memory elements which generate a large amount of heat and have different package heights are arranged on a substrate, the elastic force of the foam rubber mat causes a gap between the metal housings. There is no mention that the semiconductor memory device malfunctions due to overheating without sufficient cooling and stable operation cannot be obtained.

An object of the present invention is to overheat by effectively removing heat generated during operation when a plurality of semiconductor memory elements which generate a large amount of heat and have different package heights are mounted on a substrate. It is an object of the present invention to provide a cooling structure for a memory module which prevents a malfunction of a semiconductor memory element due to the above and obtains stable operation.

[0005]

The above object is achieved by sealing the periphery of a memory module with a polyimide film and filling an inert liquid or gel-like substance therein.

[0006]

By immersing the memory module in an inert liquid or gel-like substance, heat generated from semiconductor memory elements having different package heights during operation is removed to prevent overheating of the semiconductor memory elements. A stable operation can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the memory module includes a semiconductor memory device package 1, a printed wiring board 2, a polyimide film 3, a coolant 4, external input / output 5,
It consists of a sealing part 6 and the like. The semiconductor memory device package 1 is mounted on the printed wiring board 2 and is routed to the external input / output 5 by the wiring pattern formed on the printed wiring board 2. As shown in FIG. 2, a polyimide film 3 is stretched on the printed wiring board 2 so as to cover the semiconductor memory device package 1, and a coolant 4 is filled therein and sealed by a sealing portion 6. The coolant 4 is an inert liquid, and for example, perfluorocarbon or the like is used. When the semiconductor memory device package 1 operates, the surrounding coolant 4 takes heat, and heat is transferred to the polyimide film 3 by convection as shown in FIG. The heat is radiated to the housing and the air through the polyimide film 3. As a result, the heat generated from the semiconductor memory device package 1 is efficiently removed, and the operating temperature can be suppressed to about 80 ° C. or lower. The same effect can be obtained also in the case of the stacked memory module 10 in which the semiconductor memory device package 1 is formed into a tape carrier package and stacked vertically using a frame made of glass epoxy.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 4, the memory module comprises a laminated memory module 10, a printed wiring board 2, a polyimide film 3, a filler 7, an external input / output 5, a sealing portion 6, etc., and is placed on a main board 9 in a housing 8. Case 8
It is mounted in close contact with. The laminated memory module 10 is mounted on the printed wiring board 2 by soldering and is routed to the external input / output 5 by the wiring pattern formed on the printed wiring board 2. A polyimide film 3 is stretched on the printed wiring board 2 so as to cover the laminated memory module 10. The polyimide film 3 is filled therein with a filler 7 and sealed by a sealing portion 6. The filler 7 is an inert gel-like substance, for example, a silica-based soft gel or the like is used. When the laminated memory module 10 operates, the surrounding filler 7 takes heat, and the heat is transferred to the polyimide film 3 by heat transfer. The heat is radiated to the housing and the air through the polyimide film 3. The heat generated from the stacked memory module 10 is efficiently removed, and the temperature during operation can be suppressed to about 80 ° C. or lower. Further, when a mechanical external force is applied to the housing, as shown in FIG. 5, the filler 7 in the polyimide film 3 has an appropriate elastic force and fills the space of the housing without any gap. As a result, it is possible to prevent concentrated load from being applied to the soldered portion of the specific stacked memory module 10 on the printed wiring board 2.

Next, a third embodiment of the present invention will be described with reference to FIGS. In FIG. 6A, first, the memory module is the stacked memory module 1
0, the printed wiring board 2, and the printed wiring board 2 is entirely covered with the polyimide film 3. Next, in (b), the ultraviolet curable adhesive 11 is applied to the sealing portion 6 on the printed wiring board 2 leaving a part thereof and cured. Further, in (c), the tip of the injector 12 is inserted from the portion of the sealing portion 6 where the ultraviolet curable adhesive 11 has not been applied, and the coolant 4 is fed therein. At the last (d), the ultraviolet curable adhesive 11 is applied to the insertion portion of the injector 12 and cured to complete the whole sealing. As a result, the coolant 4 can be injected into the polyimide film with almost no bubbles left, and the heat transfer efficiency of the entire cooling structure is not impaired. Also, since ultraviolet rays are used to cure the adhesive, almost no heat is generated and the cooling agent 4 is used.
It becomes possible to perform sealing without exceeding the boiling point of.

[0010]

According to the present invention, in a memory module in which semiconductor memory device packages are arranged on a printed wiring board, heat generated from the semiconductor memory device packages during operation can be efficiently removed, so that high density is achieved. The memory module mounted in can be used. Further, since the external force applied to the housing can be dispersed appropriately to reduce the number of embossments and columns, there is an effect that the housing can be made thin and lightweight.

[Brief description of drawings]

FIG. 1 is a perspective view of a memory module showing a first embodiment of the present invention,

FIG. 2 is a vertical sectional view of a memory module showing a first embodiment of the present invention,

FIG. 3 is an explanatory diagram of heat transfer according to the first embodiment of the present invention,

FIG. 4 is a vertical sectional view of a stacked memory module showing a second embodiment of the present invention,

FIG. 5 is a vertical cross-sectional view for explaining the effect of the second embodiment of the present invention,

FIG. 6 is a process diagram of manufacturing a cooling structure for a memory module according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor memory element package, 2 ... Printed wiring board, 3 ... Polyimide film, 4 ... Coolant, 6 ... Sealing part.

Front page continued (72) Inventor Toshiharu Ishida, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa, Ltd.Production Technology Research Institute, Hitachi, Ltd. (72) Inventor Ichiro Miyano, 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi, Ltd. Production Technology Laboratory

Claims (4)

[Claims] 1. A cooling structure for a memory module, in which a semiconductor memory device package is arranged on a printed wiring board, the periphery of which is sealed with a polyimide film and an inert liquid is filled therein. 2. The printed wiring board according to claim 1, wherein the tape carrier semiconductor element is mounted on a frame provided with a recess or a hole for accommodating the tape carrier semiconductor element, and a plurality of stacked semiconductor packages are stacked in a thickness direction. Cooling structure for memory modules arranged in parallel. 3. The cooling structure for a memory module according to claim 1, wherein the sealed polyimide film is filled with a gel material. 4. The polyimide film according to claim 1, wherein the periphery of the printed wiring board is sealed with the polyimide film, an ultraviolet curable adhesive is applied and cured on most of the sealing portion, and then an inert liquid is filled with an injector. A method of manufacturing a cooling structure for a memory module in which an ultraviolet curing adhesive is applied and cured on the remaining sealing portion.