JP3378174B2 - Heat dissipation structure of high heating element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation structure for high heat generating elements.

[0002]

2. Description of the Related Art In recent years, the amount of heat generated has tended to increase with the high integration of CPUs and the like used in compact information processing devices such as notebook personal computers. On the other hand, the fine pitch of the leads of these high heat generating elements is also progressing, and T
CP (Tape Carrier Package)
For example, various mounting methods capable of coping with the fine pitch have been implemented.

As a heat dissipation structure capable of meeting these heat dissipation requirements and fine pitches, the structure shown in FIG. 3 has been generally adopted. That is, FIG. 3 (a)
In the conventional example shown in FIG. 3, thermal vias 11, 11, ... Penetrating from the element mounting surface 10 to the back surface are formed in the mounting substrate 1 on which the TCP packaged high heat generating element 3 is mounted. Further, a heat transfer block 80 and an aluminum plate 81, which are formed of a material having good thermal conductivity, are arranged on the back surface of the mounting board 1 and are in contact with the mounting board 1 via a heat transfer sheet 82.

In the conventional example shown in FIG. 3 (b),
The heat transfer block 80 is integrally formed with the aluminum plate 81. Thus, in these conventional examples, the heat generated by the high heat generating element 3 is transmitted to the heat transfer block 80 via the thermal vias 11, 11, ... And radiated from the aluminum plate 81.

[0005]

However, in the above-mentioned conventional example, since the heat dissipation route of the high heat generating element 3 is through the package portion 31 encapsulating the chip,
Thermal resistance is relatively large and heat dissipation performance is limited. Therefore, there is a drawback that the high heat generating element 3 cannot be sufficiently cooled when the amount of heat generated by the high heat generating element 3 becomes larger.

The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a heat dissipation structure for a high heat-generating element that can efficiently dissipate heat from the high heat-generating element.

[0007]

According to the present invention, the above object is to mount a high heat generating element 3 by bonding a large number of leads 30, 30 ... To the element bonding pads 2, 2 ,. while being mounted on the substrate 1, the element joining pad 2
Is provided with a heat transfer extension part 21 extending to the outside of the joint part 20 of the lead 30 , and all the heat transfer extension parts 2 are provided.
Formed by 1, 21 ... Insulating material with excellent heat conductivity
Without the heat transfer body 4 coming into contact with the high heat generating element 3
This is achieved by providing a heat dissipation structure for the high heat generating element , which is pressed against the heat transfer element 4 and absorbs the heat generated by the high heat generating element 3.

The high heat generating element 3 is mounted on the mounting substrate 1 by bonding the leads 30, 30 ... Of the high heat generating element 3 to the element bonding pads 2, 2 ,.
The element bonding pad 2 is extended outwardly and the lead 30
Heat transfer extension 21 in addition to the joint 20 where the
Is formed.

On the other hand, the heat transfer body 4 is made of an insulating material having excellent heat transfer property, and is pressed against the heat transfer extension portion 21 without contacting the high heat generation element 3, so that the heat generated from the high heat generation element 3 is led 30. , And the element bonding pad 2 to transfer heat to the heat transfer body 4.

Therefore, in the present invention, the high heating element 3
Since the heat generated in the above is drawn out of the high heat generating element 3 via the metal lead 30 having excellent heat conductivity and the element bonding pad 2, compared with the conventional example in which heat is extracted via the package section 31. The heat dissipation efficiency can be improved.

Further, since the heat conductor 4 does not directly contact the high heat generating element 3, that is, the package portion 31 and the leads 30, there is no stress load on the high heat generating element 3 and the bonding strength is low, for example, a TCP package. High heating element 3
It is also applicable to implementation of.

According to the second aspect of the invention, there is provided a heat dissipation structure having a good mounting workability. That is, in the second aspect of the present invention, the heat transfer extension portion 21 is designed in a pattern so as to be entirely arranged in the rectangular frame area 6 surrounding the rectangular area 5 including the joint portion 20 of the lead 30.

The heat transfer body 4 is formed in a tray shape having a pressing portion 40 capable of pressing the rectangular frame area 6 as a side wall, and the package portion 31 of the high heat generating element 3 is housed in a housing recess 41 formed in the central portion. The pressing portion 40 contacts all the heat transfer extension portions 21 in the housed state.

As a result, after mounting the high heat generating element 3, after covering the package portion 31 of the high heat generating element 3 with the heat conductor 4,
The heat dissipation structure according to claim 1 can be obtained by fixing the heat transfer body 4 by an appropriate means. In addition, the accommodation recess 41
When the pressing force is applied to the heat transfer body 4, the package portion 3
The transmission of the force to 1 is prevented, and the careless detachment of the lead 30 is prevented.

As described above, the heat drawn to the heat transfer body 4 is transferred to an appropriate heat radiating body and radiated from the heat radiating body. However, as described in claim 3, it is mounted as a heat radiating body. When using the heat dissipation plate 7 fixed to the substrate 1,
By interposing the heat transfer body 4 between the heat dissipation plate 7 and the mounting substrate 1 and pressing the pressing part 40 into pressure contact with the heat transfer extension part 21,
Since it is possible to stabilize the pressing force of the heat transfer body 4 to the heat transfer extension portion 21, it is possible to improve reliability, and further, the pressure contact state between the heat transfer body 4 and the heat dissipation plate 7 is achieved. Can also be stabilized. In this case, the heat transfer body 4
When a material having excellent elasticity is used as the material, the pressure contact state can be further stabilized.

Further, in the present invention, like the conventional example,
It is also possible to use a heat dissipation path via the thermal vias 11, and in this case , the mounting substrate 1 has thermal vias 11, 11 penetrating from the mounting surface 10 to the back surface of the high heat generating element 3.
.. is provided in plural, and the radiator 8 formed of a material having good thermal conductivity that contacts the thermal via 11 may be arranged on the back surface of the mounting substrate 1.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. In this embodiment, the high heat generating element 3 is a TCP packaged CPU, and is formed by pulling out a large number of leads 30, 30 ... From the side edge of the package portion 31.

Mounting board 1 on which the high heat generating element 3 is mounted
An element bonding pad 2 for bonding the lead 30 of the high heat generating element 3 is formed on the. The element bonding pads 2 are provided in four directions centering on a region where the package portion 31 of the high heat generating element 3 is arranged, and each element bonding pad 2, 2 ...
Has a joint 20 located in the rectangular area 5 to which the leads 30 of the high heat generating element 3 are joined, and a heat transfer extension 21 located outside the rectangular frame area 6. . Further, a large number of thermal vias 11 are formed on the mounting board 1. The thermal via 11 is formed by filling a small hole penetrating the mounting substrate 1 with a heat transfer metal or forming a minute through hole in the mounting substrate 1, and is formed in the arrangement region of the package portion 31 of the high heat generating element 3. It

Reference numeral 4 denotes a mounting surface 1 of the high heat generating element 3 of the mounting substrate 1.
It is a heat transfer element disposed at 0, and is formed of an insulating material having excellent thermal conductivity and flexibility. As shown in FIG. 2, the heat transfer body 4 substantially corresponds to the rectangular frame area 6 formed on the mounting substrate 1, and the heat transfer extension parts of all the element bonding pads 2 in the rectangular frame area 6 are formed. It has a pressing portion 40 and a bottom wall portion 42 that can come into contact with 21, and is formed in a tray shape having the pressing portion 40 as a side wall.

The pressing portion 40 has an outer peripheral edge dimension such that when it is mounted on the mounting substrate 1, a gap of an appropriate interval L is formed around the entire periphery of the rectangular area 5 on the mounting substrate 1. And the lead 30 on the joint 20 by the outer peripheral edge of the pressing portion 40.
Contact with is avoided. Further, the depth D of the housing recess 41 surrounded by the inner wall of the bottom wall portion 42 and the inner peripheral wall of the pressing portion 40 and formed in the central portion of the heat transfer body 4 is such that the pressing portion 40 is pushed as described later. It is slightly deeper than the mounting height of the high heat generating element 3 so as not to interfere with the package part 31 of the high heat generating element 3 even when elastically deformed.

In order to dissipate the heat transferred to the heat transfer body 4, the mounting board 1 has a heat dissipation plate 7 made of aluminum.
Is fixed. The heat radiating plate 7 is screwed to the mounting substrate 1 via the spacer 70. By making the dimension of the spacer 70 slightly shorter than the height of the heat transfer body 4, the heat radiating plate 7 is fixed. Presses the heat transfer body 4, and the pressing portion 40 is brought into pressure contact with the heat transfer extension portions 21, 21 ... Of the element bonding pads 2, 2 ...

On the other hand, on the back surface of the mounting surface 10 of the high heat generating element 3 of the mounting substrate 1, a radiator 8 composed of a heat transfer block 80 made of aluminum and an aluminum plate 81 is arranged. Therefore, in this embodiment, the high heating element 3
After being guided to the element bonding pad 2 via the lead 30 directly connected to the chip sealed in the package portion 31, the heat is transferred to the heat dissipation plate 7 via the heat transfer body 4. Then, the heat is dissipated from the heat dissipation plate 7. further,
The heat generated by the heat transfer to the package 31 is generated by the thermal via 1
1 is transmitted to the aluminum plate 81 via the heat transfer block 80 and radiated. In the figure, 82 is the heat transfer block 80 and the aluminum plate 8.
A heat transfer sheet which is interposed between the heat transfer block 80 and the aluminum plate 81 to thermally couple the heat transfer block 80 and the aluminum plate 81;
Reference numeral 83 denotes silicon grease applied to bring the mounting substrate 1 and the heat transfer block 80 into close contact with each other.

[0023]

As is apparent from the above description, according to the present invention, it is possible to secure an efficient heat dissipation route because it passes through the leads, and it is also applied to a high heat generating element having a low bonding strength. can do.

[Brief description of drawings]

1A and 1B are views showing the present invention, in which FIG. 1A is a sectional view and FIG. 1B is a plan view showing a mounting state of a high heat generating element on a mounting substrate.

FIG. 2 is a rear perspective view of a heat transfer body.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

1 Mounting board 10 Mounting surface 11 thermal vias 2-element bonding pad 20 joints 21 Heat transfer extension 3 High heating element 30 leads 31 Package Department 4 Heat transfer body 40 Pressing part 41 accommodation recess 5 rectangular area 6 rectangular frame area 7 Heat dissipation plate 8 radiator

Claims (3)

(57) [Claims] [Claim 1] a large number of by joining leads to the mounting element bonding pads on the substrate a high heat generating element is mounted on the mounting substrate
Both the the element joining pad heat transfer extension is extended is provided to the outside of the joint portion of the lead, and, all of the heat transfer extension, an insulating material excellent in heat conductivity
The heat transfer element formed by
The heat-dissipating structure of the high-heat-generating element, which is pressed against the heat transfer element to absorb the heat generated by the high-heat-generating element. 2. All the heat transfer extension parts are arranged in a rectangular frame region surrounding a rectangular region including the joint parts of all the leads, and the heat transfer body presses the rectangular frame region. The heat dissipating structure for a high heat generating element according to claim 1, wherein the portion is a side wall, and a central portion has a housing recess for housing the package portion of the high heat generating element and is formed in a tray shape. 3. A heat dissipation plate disposed at an appropriate interval from the mounting surface of the high heat generating element of the mounting board, and the heat transfer member is interposed between the heat dissipation plate and the mounting board. The pressing part of the heat transfer member is pressed against the heat transfer extension part by fixing the heat dissipation plate to the mounting substrate.
The heat dissipation structure of the high heat generating element described.