JP2000223629A - Heat radiative structure of bare ic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the heat radiation effect without increasing mounting space, by arranging a graphite sheet high in heat conductivity on the passivation film of a bare chip, and letting the heat form the bare IC go to the side of a board where the bare IC is mounted. SOLUTION: A graphite sheet 7 high in heat conductivity on roughly the same level as a bump 3 is arranged on the passivation film of a bare IC2 where a bump 3 is made at each electrode, and the bump 3 of the bare IC is joined with the land 4 provided on a board 1. Then, the electric continuity between the bare IC2 and the electric circuit made on the board 1 is taken, and a sealing resin 6 is let flow in the gap between the bare IC2 and the board 1 and is thermoset to perform the protection of the electric junction and the fixation of the bare IC. The heat generated in the bare IC2 is conducted to the board 1 through the graphite sheet 7 from the rear b of the bare IC besides the heat radiation into the air from the surface a of the bare IC, thus the heat radiation utilizing the whole of the board becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiating structure of a bare IC on an electric circuit board which requires mounting of a high heat generating bare IC centering on a power supply system.

[0002]

2. Description of the Related Art According to a conventional bare IC connection method, a bump formed on a bare IC is bonded to a land provided on a substrate side, and a gap between the bare IC and the substrate is sealed and fixed with a resin. There is.

FIG. 6 shows a conventional bare I mounted on a substrate.
C is a plan view, and FIG. 7 is a cross-sectional view taken along the line DD of FIG. 6 and 7, a bump 3 is formed on each of the bare ICs 2 having four electrodes, and the bumps 3 are bonded to the lands 4 provided on the substrate 1, so that the bare IC 2 and the substrate 1
Electrical continuity with the electric circuit (wiring pattern 5) formed thereon is established. Thereafter, the sealing resin 6 is poured into the gap between the bare IC 2 and the substrate, and is thermally cured to protect the electrical joint and fix the bare IC.

In this case, bare I is exposed on the surface.
Only the front surface a of C2, the back surface b, and the four side surfaces c are covered with the sealing resin 6.

[0005] The sealing resin is used to protect the joint of the bare IC and the bare I.
It is used for the purpose of securing reliability such as fixing of C. Generally, the resin used for sealing does not use a material with good thermal conductivity, so the heat generated in the bare IC is confined by the sealing resin layer Will be.

Therefore, in the case of a bare IC which generates a large amount of heat, such as a power supply system, heat is not effectively released in a normal state.
As shown in the cross-sectional view of FIG. 8, a heat radiation plate 9 is added on the surface a of the bare IC 2 or an air cooling system is provided in a housing on which a board on which the bare IC is mounted is mounted. Efforts are being made to improve the heat dissipation effect from the surface.

[0007]

However, in the above countermeasures, the height of parts is increased by adding a heat sink, and
Adding an air cooling system increases the size of the housing. In general, products on which bare ICs are mounted are required to be light, thin and small, and there is a problem that it is difficult to satisfy the required conditions required for the products.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a heat dissipation structure which can mount a high heat generation bare IC in a space-saving manner while maintaining a heat dissipation effect.

[0009]

According to the present invention, a graphite sheet having high thermal conductivity is arranged on a passivation film portion of a bare IC to solve the above-mentioned problems and achieve the object.
By dissipating the heat generated from C to the substrate on which the bare IC is mounted, the heat radiation effect can be improved without increasing the mounting space.

[0010] Further, the heat dissipation from the bare IC is released to the substrate side on which the bare IC is mounted by a heat radiation pattern provided on the substrate side so as to be in contact with the graphite sheet disposed on the passivation film portion of the bare IC. The heat radiation effect can be improved without increasing the space.

Further, the heat radiation pattern provided on the substrate is drawn out to the outside of the bare IC, and the heat generated from the bare IC is released to the surface of the substrate outside the bare IC, thereby improving the heat radiation effect without increasing the mounting space. Can be.

In addition, the graphite sheet disposed on the heat radiation pattern drawn to the outside of the bare IC can dissipate heat generated from the bare IC over a wider area on the substrate without increasing a mounting space.

In addition, the graphite sheet arranged on the surface of the wiring pattern connected to the bare IC can improve the heat radiation effect over a wider area on the substrate without increasing the mounting space.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a plan view of a bare IC according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. 1 and 2, reference numeral 7 denotes graphite having high thermal conductivity. In addition, the same members as those in FIGS. 6 to 8 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIGS. 1 and 2, a graphite sheet 7 having substantially the same height as the bump 3 (the height after mounting the bare IC) is provided on the passivation film portion of the bare IC 2 having the bump 3 formed on each electrode. Are arranged (attached), and the bumps 3 of the bare IC are joined to the lands 4 provided on the substrate 1, so that conduction between the bare IC 2 and the electric circuit (wiring pattern 5) formed on the substrate 1 is established. Take, bare IC2
The sealing resin 6 is poured into the gap between the substrate and the substrate 1 and thermally cured to protect the electrical joint and fix the bare IC.
Thus, a heat dissipation structure of the bare IC is realized.

The difference between the present embodiment and the conventional structure is that, as shown in FIG. 2, the sealing resin 6 is normally filled between the bare IC 2 and the substrate 1, but instead of the sealing resin 6, graphite is used. The sheet 7 is sandwiched.

The heat generated by the bare IC 2 is transmitted from the bare IC back surface b to the substrate 1 via the graphite sheet 7 together with the heat radiation from the bare IC surface a into the air, and the heat can be dissipated utilizing the entire substrate. . In place of sealing resin with low thermal conductivity, graphite sheet with high thermal conductivity is bare I
The space between C and the substrate is satisfied, and as a result, the heat generated by the bare IC is further transmitted to the substrate.

In the present embodiment, it is intended that a structure in which a graphite sheet is sandwiched between a bare IC and a substrate is used. For example, a heat dissipation structure such as mounting a bare IC on a substrate to which a graphite sheet has been pasted is used. There is no particular limitation on the procedure of implementation for realizing.

(Embodiment 2) FIG. 3 is a plan view of a bare IC according to Embodiment 2 of the present invention, FIG. 4 is a cross-sectional view taken along line BB of FIG. 3, and FIG. 5 is a line CC of FIG. FIG. FIG.
In FIG. 5 to FIG. 5, reference numeral 8 denotes a heat radiation pattern, and the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

First, the substrate surface a on which the bare IC 2 is mounted
A normal wiring pattern 5 and a heat radiation pattern 8 are provided in the portion. The heat radiation pattern 8 is drawn out of the bare IC 2. The wiring pattern 5 and the heat radiating pattern 8 are basically patterned so as not to be short-circuited. In addition to the portion directly below the bare IC, if the space allows, the patterning is performed over a wide range according to the calorific value of the bare IC.

Next, the wiring pattern 5 and the heat radiation pattern 8
The graphite sheet 7 is placed (attached) on the surface of. However, the graphite sheet stuck on the wiring pattern does not overlap with the land 4 and the graphite sheet 7 stuck on the heat radiation pattern directly under the bare IC
Is equal to the height of the bump 3 after the bare IC 2 is mounted.

Next, a bare IC is mounted on the substrate by a usual method. Thus, a heat dissipation structure of the bare IC is realized.

The heat generated by the bare IC is transferred to the bare IC surface a.
The heat is transmitted from the bare IC back surface b through the graphite sheet 7 to the heat dissipation pattern 8 on the substrate back surface b, and is transmitted to a region other than the portion immediately below the bare IC together with the heat release from the bare IC. The heat dissipation pattern allows for more effective heat dissipation over a wider area and the graphite sheet.

The same heat radiation effect can be obtained by using a graphite sheet attached to the surface of the wiring pattern 5.

[0026]

As described above, the present invention provides a bare IC
By disposing a graphite sheet having high thermal conductivity in the passivation film portion and releasing heat from the bare IC to the substrate side on which the bare IC is mounted, the heat radiation effect can be improved without increasing the mounting space.

[0027] Further, the heat dissipation from the bare IC is released to the board side on which the bare IC is mounted by a heat radiation pattern provided on the substrate side so as to be in contact with the graphite sheet disposed on the passivation film portion of the bare IC. The heat radiation effect can be improved without increasing the space.

Further, the heat radiation pattern provided on the substrate is drawn out to the outside of the bare IC, and the heat generated from the bare IC is released to the surface of the substrate outside the bare IC, thereby improving the heat radiation effect without increasing the mounting space. Can be.

Further, the heat generated from the bare IC can be dissipated over a larger area on the substrate without increasing the mounting space, by the graphite sheet disposed on the heat radiation pattern drawn to the outside of the bare IC.

In addition, the graphite sheet disposed on the surface of the wiring pattern connected to the bare IC can improve the heat radiation effect over a wider area on the substrate without increasing the mounting space.

[Brief description of the drawings]

FIG. 1 is a plan view of a heat dissipation structure of a bare IC according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a plan view of a heat dissipation structure of a bare IC according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a sectional view taken along the line CC of FIG. 3;

FIG. 6 is a plan view of a bare IC mounted on a conventional substrate.

FIG. 7 is a sectional view taken along the line DD in FIG. 6;

FIG. 8 is a cross-sectional view of a bare IC mounted on a substrate having a heat sink on the surface of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 bare IC 3 bump 4 land 5 wiring pattern 6 sealing resin 7 graphite sheet 8 heat radiation pattern 9 heat radiation plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshifumi Kitayama 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5F036 AA01 BB21 BD11

Claims (5)

[Claims] 1. A bare IC for dissipating heat from the bare IC to a substrate side on which the bare IC is mounted to improve a heat radiation effect.
A heat dissipating structure for bare ICs, wherein a graphite sheet having high thermal conductivity is arranged on the passivation film portion of C. 2. A bare IC for dissipating heat generated from the bare IC to the board side on which the bare IC is mounted to improve a heat radiation effect.
A heat radiating structure for a bare IC, wherein a heat radiating pattern is provided on the substrate side so as to be in contact with the graphite sheet disposed on the passivation film portion of C. 3. A bare IC wherein a heat radiation pattern provided on the substrate is drawn out to the outside of the bare IC in order to release heat generated from the bare IC to a surface of the substrate outside the bare IC to improve a heat radiation effect. Heat dissipation structure. 4. A heat dissipating structure for a bare IC, wherein a graphite sheet is arranged on a heat dissipating pattern drawn to the outside of the bare IC in order to dissipate heat generated from the bare IC over a wider area on the substrate. . 5. A bare IC wherein a graphite sheet is arranged on a surface of a wiring pattern connected to the bare IC in order to improve a heat radiation effect over a wider area on the substrate.
Heat dissipation structure.