JPH07231053A - Heat radiating structure of heating element - Google Patents

Abstract

PURPOSE:To improve the radiation feature of a heating element by forming in a board through holes that allow the insertion and withdrawal of the heating element, forming projections on the top of a heat radiating body inserted into the through holes, bringing the heat radiating surfaces of the heating elements into tight contact with the top of the projections, and pressing the heating elements against the heat radiating body by plate springs. CONSTITUTION:Through holes 7a corresponding to heating elements 10 are formed in a board 7, and projections 8a are formed on a heat radiating body 8 which can be inserted into the through holes 7a. The projections 8a are inserted into the through holes 7a, and the heating elements 10 are brought into tight contact with the top of the projections with thermal conductive compound in-between. The heating elements 10 are then enclosed with a sealing frame 13, the top of which is sealed with a sealing capper 14 to hermetically seal the heating elements 10. The sealing capper 14 has plate springs 15 that are positioned facing toward the heat radiating body 10 and press the heating elements 10 against the heat radiating body 8. This improves the heat radiation efficiency of the heating elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-dissipating structure for heat-dissipating a heat-dissipating member such as an electronic component mounted on an insulating substrate by TAB for cooling.

[0002]

2. Description of the Related Art FIG. 3 is a side sectional view showing a heat dissipating structure of a conventional heat generating element, showing a structure in which a heat dissipating element typified by heat dissipating fins is mounted on a heat generating element, for example, a package such as a semiconductor element. It is explained using an example. In the figure, reference numeral 1 denotes a thin plate substrate having an insulating property, and has a notch 1a having a step for mounting a heating element described later in the plate thickness direction, and the notch 1a. A large number of thermal vias 2 are provided at a predetermined pitch so as to penetrate from the bottom surface of the substrate 1a to the back surface side of the substrate 1 and which is filled with a substance having good thermal conductivity, for example, a thick film metal paste or the like.

Reference numeral 3 denotes TA on the cutout portion 1a of the substrate 1.
B is a heating element consisting of mounted semiconductor elements,
A plurality of lead wires 3a serving as AB are spread out around the lead wires 3a, and TAB connection is made to a contact formed on the substrate 1 by soldering or the like. An adhesive layer 4 adheres the heating element 3 to the cutout portion 1a of the substrate 1, and is made of a resin having heat conductivity, for example, silver paste.

Reference numeral 5 denotes a heat radiator adhered to the entire back surface of the substrate 1 via an adhesive layer 6 having a predetermined thickness. With such a configuration, when the heating element 3 operates, it generates heat, but the heat generated during this operation is
To the thermal via 2 via the adhesive layer 4, and is conducted to the back surface of the substrate 1 by the thermal via 2. Then, the heat is conducted from the back surface side of the substrate 1 to the radiator 5 through the adhesive layer 6. Heat is radiated by the body 5, and the heat radiating action of the heat radiating body 5 radiates and cools the heat generating body 3.

[0005]

However, in the above-mentioned conventional technique, the adhesive layer 2 is provided between the heating element 3 and the front surface of the substrate 1 and between the back surface of the substrate 1 and the heat radiator 5, respectively. The adhesive layer 6 is interposed, and both of the adhesive layers 2 and 6 are formed by the screen printing technique.
There is a problem in that it is difficult to form 6 and 6 uniformly and in a thin film shape. Further, when screen-printing these adhesive layers 2 and 6, there is also a problem that air gaps tend to be formed, and according to this, the state of adhesion between the heating element 3 and the radiator 5 cannot be said to be ideal. However, it was not technically satisfactory to obtain a reliable heat radiation effect.

The present invention has been made in order to solve the above-mentioned problems, and by forming a thin and uniform adhesive layer without forming bubbles in the adhesive layer, the thermal resistance of the adhesive layer is small and heat dissipation is achieved. The object is to realize a heat dissipation structure for a heating element having excellent properties.

[0007]

In order to achieve the above-mentioned object, according to the present invention, a heat-dissipating body is adhered to the back surface of a substrate having a heat-dissipating body mounted on the front surface side through a plurality of lead wires, and the heat-dissipating body is adhered to the back surface. In a heat dissipation structure of a heating element that dissipates heat generated from the outside by a radiator, the substrate is formed with a through hole having an inner diameter large enough for the heating element to be easily taken in and out, and Forms a protrusion having a height such that the upper end surface is exposed on the surface of the substrate when inserted into the through hole from the lower surface side, and the heating element is attached to the upper end surface of the protrusion through a heat conductive compound. Close to the radiator,
The heating element including the lead wires is surrounded by a sealing frame, and the upper surface of the sealing frame is arranged to face the heating element mounted in the sealing frame so that the heating element is located on the radiator side. The heating element is hermetically sealed by sealing with a sealing cap provided with a leaf spring that presses against.

[0008]

According to the above-described structure, when the radiator is adhered to the lower surface side of the substrate by using the adhesive layer, the projection formed on the radiator is inserted into the through hole formed in the substrate, and the front surface side of the substrate is inserted. To expose. Then, a heating element is mounted on the exposed protrusion via a heat conductive compound, and the heating element is TAB mounted on the substrate by a lead wire extending around the heating element.

After that, the periphery of the heating element including the lead wires is surrounded by a sealing frame, and the upper surface of the sealing frame is sealed by a sealing cap. This sealing cap has
Leaf springs are provided so as to face each other above the heating element, and by sealing the sealing frame with a sealing cap,
The leaf spring makes contact with the upper surface of the heating element and presses it toward the radiator, and the heating element is brought into close contact with the radiator directly via the heat conductive compound.

As a result, the heating element is brought into close contact with the radiator, so that the heat generated by the operation of the heating element is directly transferred to the radiator through the heat conductive compound, and the radiator efficiently and externally. Is radiated to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a heat dissipation structure of a heating element of the present embodiment. In the figure, 7 is a thin plate substrate having an insulating property, and a heating element to be described later is mounted in the plate thickness direction. Therefore, the through hole 7a having an inner diameter large enough for the heating element to be easily taken in and out is provided.

Reference numeral 8 denotes a radiator which is adhered to the back side of the substrate 7 via an adhesive layer 9, and the surface of the radiator 5 has
A protrusion 8a having an outer shape that can be easily put into and taken out of the through hole 7a is formed in an arrangement corresponding to the arrangement of the through hole 7a. Reference numeral 10 is a heating element provided on the upper end surface of the projection 8a of the radiator 8, and is provided via a heat conductive compound 11. That is, the heating element 10 is not fixed by the compound 11 interposed in the radiator 8.

Reference numeral 12 denotes a lead wire having a function of a plurality of TABs extending from the upper surface of the heat generating body 10 to the periphery, and on a protrusion 8a of the heat radiating body 8 inserted into the through hole 7a. When the heating element 10 is arranged in the substrate 7, the TAB connection is made to the substrate 7 arranged so as to surround the periphery thereof through a plurality of contacts formed on the surface of the substrate 7.

Reference numeral 13 denotes a lead wire 1 around the heating element 10.
A sealing frame, which includes 2 and is arranged so as to be surrounded by a frame material having a predetermined height, 14 is an upper surface of the sealing frame 13 which is opened so as to seal the heating element 10 together with the sealing frame 13. The sealing cap 14 is provided with a leaf spring 15 corresponding to the position where the heating element 10 is arranged. Tongue portion 15 formed in four directions by notching in
It is formed by bending a downward, and the tongue-shaped leaf spring 15 presses the heating element 10 downward from the upper surface side thereof, that is, toward the radiator 8.

Reference numeral 16 denotes a sheet interposed between the leaf spring 15 and the heating element 10, which is made of a heat conductive material.
It will be pushed by 5 toward the radiator 8. Also,
Reference numeral 17 is a positioning pin for fixing the leaf spring 15 at a predetermined position of the sealing cap 14.

Here, the procedure for assembling the heat dissipation structure having the above-described structure will be described. First, a through hole 7a having a size corresponding to the outer shape of the heating element 10 is formed in the substrate 7, and then the heating element 1 is formed.
A TAB connection is made between the lead wire 12 which is previously connected to 0 and the contact on the substrate 7 side. Next, the thermal conductive compound 11 is applied to the protrusions 8 a of the radiator 8 and the adhesive layer 9 is applied to the substrate 7 or the radiator 8. And
The radiator 8 is adhered to the substrate 7 via the adhesive layer 9, and the heating element 10 is provided on the protrusion 8 a of the radiator 8.
At this time, the substrate 7 and the radiator 8 are fixed to each other by the adhesive layer 9, but the heating element 10 is the heat conductive compound 1.
Due to 1, it is not fixed to the radiator 8.

In this state, after the sheet 16 is inserted above the heating element 10, the sealing frame 13 surrounds the heating element 10 and the lead wire 12 and is fixed to the periphery thereof. on the other hand,
The position corresponding to the upper portion of the heating element 10 on the back surface of the sealing cap 14, that is, the position where the leaf spring 15 is formed is positioned by the positioning pin 17 so that the leaf spring 15 is fixed, and the leaf spring 15 is fixed. I'll do it.

In this way, the heating element 10 and the substrate 7 are hermetically sealed by using the sealing cap 14. This allows
By the reaction force of the leaf spring 15 that has been bent inward in advance,
The heating element 10 is pressed by the radiator 8. In this way, the heating element 10 mounted in the TAB can be surely brought into close contact with the radiator 8, and as a result, the heat generated from the heating element 10 is efficiently transmitted to the radiator 8 and is radiated to the outside by the radiator 8. Thus, the heating element 10 has a cooling effect.

In the above-described embodiment, one radiator 8 is mounted on one substrate 7, but the case where one or more radiators 8 are mounted is shown in FIG. 2 shows.
FIG. 2 is a schematic view showing a heat dissipation structure of another embodiment. As shown in this drawing, a plurality of heating elements 1 are provided on one substrate 7.
If 0 is mounted, the mounted heating element 10
If the number of leaf springs 15 corresponding to the number of the above is formed in the sealing cap 14 and this sealing cap 14 is used, all the heating elements 10 can be similarly and surely provided by one sealing cap 14. In addition, it is possible to provide a structure in which the heat radiator 8 is brought into close contact with each other, and thereby, a plurality of heat radiators 8 can be cooled at the same time.

[0020]

As described above, according to the present invention, a heat radiating body is adhered to the back surface of a substrate having a heat generating body TAB mounted on the front side via a plurality of lead wires, and heat generated from the heat generating body is adhered. In a heat dissipation structure of a heat generating element for radiating heat to the outside by a heat radiating body, a through hole having an inner diameter large enough for the heat generating element to be easily put in and out is formed in the substrate, and the through hole is formed in the heat radiating body. A protrusion having a height such that the upper end surface is exposed on the surface of the substrate when inserted from the lower surface side, and the heating element is formed on the upper end surface of the protrusion as a heat radiator through a heat conductive compound. Adhere closely, enclose this heat-generating element including the lead wire with a sealing frame, and
The upper surface of the sealing frame is arranged so as to face the heating element mounted in the sealing frame, and the heating element is sealed by a sealing cap provided with a leaf spring that presses the heating element toward the radiator. It was decided to hermetically seal.

Therefore, the heating element which has been conventionally fixed only by the adhesive layer can be directly pressed against the radiator by the leaf spring via the heat conductive compound, so that the adhesion between the heating element and the radiator is improved. As a result, the adhesive layer can be held, and as a result, the adhesive layer, which has been required in the past by a predetermined amount (predetermined thickness), can be thinned and can be applied uniformly. As a result, the thickness of the adhesive layer that can be formed with a normal silver epoxy adhesive was about 20 μm, but according to the example of the present application, the thickness is more than about 10 μm.
It was possible to reduce the thickness to less than μm.

Therefore, the heat radiation efficiency of the heating element can be improved, and the thermal resistance value is about 2.5 ° C./°C of the temperature obtained by the structure of the conventional example using the normal thermal via.
Compared with w, about 1.6 ° C./W could be achieved in the example of the present invention. Further, even if a plurality of heating elements are mounted, it is sufficient to form a plurality of leaf springs on the sealing cap corresponding to each heating element and press all the heating elements with each of these leaf springs. According to this, since there is little variation in the thickness of the adhesive layer, it is possible to obtain a stable heat dissipation effect with low thermal resistance.

[Brief description of drawings]

FIG. 1 is a schematic view showing a heat dissipation structure of a heating element of this embodiment.

FIG. 2 is a schematic view showing a heat dissipation structure of a heating element of another embodiment.

FIG. 3 is a schematic view showing a heat dissipation structure of a heating element of a conventional example.

[Explanation of symbols]

 7 Substrate 7a Through Hole 8 Radiator 8a Protrusion 9 Adhesive Layer 10 Heating Element 11 Thermal Conductive Compound 12 Lead Wire 13 Sealing Frame 14 Sealing Cap 15 Leaf Spring 15a Tongue Piece

Claims (1)

[Claims] 1. A heat radiator is adhered to the back surface of a substrate on which a heat generator is mounted on the front surface side through a plurality of lead wires, and the heat generated by the heat radiator is radiated to the outside. In the heat dissipation structure of the heating element, a through hole having an inner diameter large enough for the heating element to be easily inserted and removed is formed in the substrate, and the radiator is inserted into the through hole from its lower surface side. Sometimes, a protrusion having a height such that the upper end surface is exposed on the surface of the substrate is formed, and the heating element is adhered to the radiator on the upper end surface of the protrusion through a heat conductive compound. A plate that surrounds the heating element including the lead wires with a sealing frame, and arranges the upper surface of the sealing frame to face the heating element mounted in the sealing frame and presses the heating element toward the radiator. Sealed with a sealing cap equipped with a spring Heat radiation structure of the heat generating element, wherein a heating element hermetically sealed Te.