JPH02144998A - Printed circuit board unit cooling structure - Google Patents

Abstract

PURPOSE:To uniformly cool electronic parts mounted on a printed circuit board unit so as to improve the cooling efficiency by forming heat radiating structure bodies by fitting, as required, heat radiating piece sections to base sections joined to the electronic parts through studs. CONSTITUTION:A heat radiating structure body 20 is constituted of a heat radiating section 21 provided with fins, a stud 22 (short) or 23 (long) to be coupled with the heat radiating section selected, as required, out of plurality of kinds of studs 22 and 23 having different lengths, and base section 24 which supports the stud and is fitted to the upper section of electronic parts, such as LSI, etc. When the structure body 20 is fitted to an LSI 25, the height of the section 21 of the structure body 20 of an LSI 8 with heat radiating fins mounted on an upper part of a printed circuit board 7 is made higher than that of the section 21 of an LSI 8 mounted on a lower part of the circuit board 7 in a state where the circuit board 7 is housed in a printed circuit board mounting frame 5. When such structure is used, the ambient temperature of the LSIs can be uniformized and the junction temperature at each LSI can be reduced.

Description

[Detailed Description of the Invention] [Summary] A plurality of printed board units each having a plurality of electronic components such as LSIs mounted on a printed board are arranged at intervals to constitute one electronic bag, and the printed board unit Regarding the structure that cools electronic components by forcing cooling air to flow between them, the upper electronic components are not affected by the heat generated by the lower electronic components, and the shape of the heat dissipation fins is designed so that the ventilation is not obstructed. The purpose of this is to uniformly cool the electronic components mounted on the printed circuit board unit and increase cooling efficiency.The heat dissipating piece is attached to the base part connected to the electronic component via a stud as necessary. Installed to form a heat dissipation structure, the heat dissipation structure using relatively long studs is attached to the lower electronic components of the printed board unit, and relatively short studs or no studs are used to the upper electronic components. A cooling structure for a printed board unit is constructed, which is characterized by having a heat dissipation structure attached thereto.

[Industrial application field]

The present invention relates to a cooling structure for communication/information equipment, in particular, a cooling structure for cooling a printed board unit in which electronic components such as large scale integrated circuits (LSI) are mounted on a printed board while the printed board unit is housed in a shelf.
The present invention relates to a cooling structure for a printed board unit.

Electronic circuits in communication and information equipment are rapidly becoming faster and more dense, and the use of highly integrated gate arrays and custom LSIs has increased more than ever before. As a result, the heat density of the printed board unit on which the LSI is mounted has become extremely high, and how to cool it has become an important issue in configuring the equipment. As a cooling method for this type of equipment, a forced air cooling method using a fan is generally used for reasons of maintainability and economy.

[Conventional technology]

The conventional forced air cooling structure for cooling printed board units is
As shown in Figs. 5 and 6, a large-scale integrated circuit with heat dissipation fins (LSI) is a highly integrated LSI with heat dissipation fins attached.
I) A plurality of 8 are mounted on a printed board 7 to form a printed board unit 6, and several of these printed board units 6 are arranged in parallel in vertical rows within a printing board unit mounting frame 5 called a shelf. A fan unit 2 consisting of a fan mounting frame 3 and a fan 4 is attached to the upper part of the electronic device 1, and a printed board unit 6 is configured.
In between, a fan 4 is used to forcefully flow air from below to above for cooling.

In the figure, 9 is a connector for electrically connecting the printed board unit to a backboard connector (not shown) on the back side of the shelf 5, and IO is a connector on the front side of the printed board unit 6 to prevent air leakage. The front plate attached to the front plate is shown.

When the printed board unit 6 is cooled with such a conventional cooling structure, as shown in Fig. 7, when cooling air is flowed between the printed board units 6, the upper part (point 0 in Fig. 6) is affected by the heat generated by the LSI in the lower part. As a result, the ambient temperature becomes significantly higher than that at the lower part (point A in FIG. 6), and the temperature difference between the junctions of each LSI becomes significant depending on the upper and lower positions. In addition, due to the ventilation resistance of the heat dissipation fins at the bottom, the LSI at the top (point 0 in Figure 6)
It becomes difficult to secure sufficient ambient wind speed necessary for cooling, and the relative temperature at the lower part (point A in Figure 6) becomes significantly higher. In addition, in FIG. 7, for ambient temperature and ambient wind speed, values at positions A, B, and C in FIG. 6 are shown, and for junction temperature, values at positions A, B, and C in FIG. 6 are shown.
The temperature of the LSI directly above B and C is shown. Further, the numerical values on the vertical axis scale indicating temperature and wind speed in FIG. 7 are for comparison, and do not indicate absolute values.

[Problem to be solved by the invention]

As described above, in the conventional cooling structure, the cooling effect differs depending on the position of the LSI mounted on the printed board unit, and as a result, it is difficult in some parts to secure the ambient temperature and wind speed necessary for cooling. Cooling performance will not be obtained. The result affects the circuit function, reduces the margin of circuit operation, and may cause malfunction or damage. In the conventional cooling structure, the reason why the junction temperature of the LSI differs significantly is that the upper LSI is affected by the heat generated by the lower LS and I, as well as the reduction in wind speed due to the ventilation resistance of the lower heat dissipation fins. This is because.

Therefore, in the present invention, the upper LSI is not affected by the heat generated by the lower LSI, and the electronic components such as the LSI mounted on the printed board unit are designed to have a heat dissipating fin shape that does not obstruct ventilation. The purpose is to equalize the cooling of the equipment and increase cooling efficiency.

[Means to solve the problem]

In order to solve such problems, in the present invention, an electronic device is constructed by arranging a plurality of printed board units in which a plurality of electronic components are mounted on a printed board in parallel at intervals, and the printed board unit In the structure in which electronic components are cooled by forcing cooling air to flow between them, various heat radiating structures having different heights to the heat radiating portion are attached to the upper portions of the plurality of electronic components.

In addition, in the above cooling structure, a heat dissipation structure is constructed by attaching a heat dissipation section to the base part joined to the electronic component via studs of various lengths as necessary, and It is characterized in that a heat dissipation structure using relatively long studs is attached to the component, and a heat dissipation structure using relatively short studs or no stand is attached to the upper electronic component.

[For production]

According to the present invention, first of all, by attaching various heat dissipation structures with different heights to the heat dissipation pieces on top of a plurality of electronic components, the flow of cooling air is adjusted according to the location on the printed board. can be controlled appropriately.

Second, a heat dissipation structure using relatively long studs is attached to the lower electronic components of the printed board unit, and a heat dissipation structure using relatively short studs or no studs is attached to the upper electronic components. , the cooling air flows upward through the studs of the heat dissipation structure of the lower electronic components. Therefore, the upper electronic components are less affected by the heat generated by the lower electronic components, and ventilation is not obstructed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 4. First, as specifically shown in FIG. 1, the heat dissipation structure 20 includes a heat dissipation part 21 having fins, and a plurality of types of studs 22 (short) or 23 (long) having different lengths connected to the heat dissipation part. ) and support this stand and LS
It consists of a base part 24 attached to the upper part of an electronic component 25 such as I. These members have a structure in which the height from the LSI 25 to the heat dissipation section 21 can be easily changed by arbitrarily combining these members with a screw structure or fitting.

When attaching the heat dissipation structure 20 to the LSI 25, as shown in FIG. The height of the heat dissipation section 21 of the heat dissipation structure 20 of the LSI 8 is set to be high (for example, it is connected via a long stud 23), and the height of the heat dissipation section 21 is made lower as the upper part becomes higher (for example, it is connected via a long stud 23). L with heat radiation fins on top
For SI8, the heat dissipation section 21 is attached directly to the base section 24 of the LSI without using a stud).

With this configuration, the structure is such that the upper LSI is not affected by the heat generated by the lower LSI as much as possible.

In order to further increase the effect, the upper and middle heat dissipation parts 21
An airflow guide plate 31 is provided adjacent to the airflow guide plate 31 .

In Fig. 2, arrows indicate the flow of air; black arrows indicate the flow of cold air, and black arrows indicate the flow of warm air. In this way, the air that has passed through the heat radiating section 21 and has become warm is guided by the airflow guide plate 31, and does not affect the heat radiating section 21 located at the upper position, and the cold air that has passed through the studs 22 and 23 is guided at the upper position. This corresponds to the heat dissipation section 21 of.

With the above structure, it is possible to equalize the ambient temperature of the LSI, thereby reducing the difference in junction temperature between each LSI. In addition, the size and shape (for example, the cross-sectional area of the stand, the size of the fins, the number of fins) and the material (the heat of the fins By using different resistances (large and small), it is possible to make the junction temperature more uniform. In addition, it is also effective to subject the surfaces of the studs 22 and 23 to heat insulation treatment using a well-known technique to prevent heat radiation from these parts.

Next, in FIG. 3 showing an embodiment of the present invention, 1 is an electronic device in which a large number of printed board units 6 are mounted on a printed board unit mounting frame 5, and 2 is a fan unit for cooling the electronic device 1, which is mounted with a fan. It consists of a frame 3 and a fan 4. In addition, 41° 42.43 in the figure are LSIs with heat dissipation fins mounted on the printed board 7, and the height of the heat dissipation fins (heat dissipation part) of these LSIs is such that they are mounted at the bottom (at a position far from the fan unit 2). It has become extremely expensive.

In the figure, reference numeral 21 indicates a heat dissipation section having heat dissipation fins, 22 and 23 indicate studs, and 24 indicates a base section.

Further, in the figure, numeral 31 indicates an airflow guide plate for separating the flow of cold air and warm air, and the guide plate is fixed to the printed board 7 with studs 44 and screws 45.

In Figure 4, the values for ambient temperature and ambient wind speed at positions A, B, and C in Figure 2 are shown, and for the junction temperature, the values are shown at L directly above positions A1B and C in Figure 2.
Indicates the temperature of SI. Further, the numerical values on the vertical axis scale indicating temperature and wind speed in FIG. 4 are for comparison and do not indicate absolute values.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the influence of heat generation from the lower LSI, lower the ventilation resistance of the radiation fins, and easily secure the wind speed necessary for cooling. Furthermore, as shown in Fig. 4, when the present invention is used compared to the conventional method, the LSI ambient temperature difference and LSI junk temperature difference depending on the mounting position are reduced, preventing the decrease in circuit operating margin due to temperature difference and stabilizing the LSI. It is possible to ensure proper circuit operation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a heat dissipation structure according to the present invention, FIG. 2 is a cooling structure according to the present invention, FIG. 3 is a perspective view showing an embodiment of the present invention, and FIG. 4 is an inside view of an apparatus using the cooling structure according to the present invention. 5 is a perspective view of a conventional cooling structure, FIG. 6 is a sectional view of a conventional cooling structure, and FIG. 7 is a diagram showing ambient temperature and ambient wind speed inside a device using a conventional cooling structure. It is a figure showing ambient wind speed. 5... Printed board unit mounting frame, 7... Printed board,... LSI with heat radiation fins, 0... Heat radiation structure, 21... Heat radiation part, 2...
Stat (short), 23... Stat 4... Base part,
25...LSI, 1...Airflow guide plate. (long)

Claims (2)

[Claims] 1. An electronic device (1) is constructed by arranging a plurality of printed board units (7) with a plurality of electronic components (8, 25) spaced apart from each other, and cooling air is distributed between the printed board units. In the structure in which electronic components are cooled by forced circulation, various heat dissipation structures (20) having different heights to the heat dissipation part (21) are attached to the top of the plurality of electronic components (25). A cooling structure for printed board units featuring: 2. The electronic device (1) is configured by vertically arranging a plurality of printed board units, each having a plurality of electronic components (8, 25) mounted on a printed board (7), at intervals, and between the printed board units. In a structure that cools electronic components by forcing cooling air to flow from the bottom to the top, studs (22, 23) are installed as necessary on the base portion (24) that is joined to the electronic component (25). A heat dissipation structure (20) is constructed by attaching a heat dissipation section (21) through the PCB unit, and a heat dissipation structure (20) using relatively long studs (23) is attached to the electronic components at the bottom of the printed board unit. A cooling structure for a printed board unit, characterized in that a heat dissipation structure (20) using a relatively short stud (22) or not using a stud is attached to an electronic component.