JPS616845A - Production of thermal sprayed substrate - Google Patents

Abstract

PURPOSE:To obtain a thermal sprayed substrate whose mounting face has good flatness, by providing the metal substrate with concave warpage before the sandblasting process. CONSTITUTION:A 1.5mm. thick aluminum plate is press cut in an ordinary manner to obtain a 7cm long and 4cm wide metal substrate 1 with fitting holes 4. When this substrate is packaged, it is mounted on a radiating plate while the face thereof having shear drop 11 due to the press cutting (lower face) is faced to the radiating plate so that the opposite face (upper face) is thermal sprayed. The substrate is then provided with warpage of a magnitude (d) of about 0.15mm. such that the thermal spraying face becomes concave. The thermal spraying face is wholly roughened by the ordinary sandblasting. The metal substrate 1, after the sandblasting, obtains good flatness with little warpage. Alumina ceramics is thermal sprayed on the substrate to form an insulation layer 2 and then copper is thermal sprayed on the surface of the insulation layer 2 and on the surface of the metal substrate not coated with ceramics so as to form a thermal sprayed film 3.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a thermal sprayed substrate that is used for mounting on a semiconductor heat sink, and in particular is used as a method for manufacturing a thermal sprayed substrate for semiconductor devices such as modules. It is something that

[Technical Background of the Invention] FIG. 2 shows the structure of a typical thermal sprayed substrate. This structure is almost the same as that produced by the manufacturing method of the present invention and that produced by the conventional method. FIGS. 2(a) and 2(b) are a plan view and a side view of the thermal sprayed substrate A, respectively. 1 is a metal substrate (for example, an aluminum substrate), 2 is an insulating sprayed film (for example, a ceramic sprayed film), and 3 is a metal sprayed film (for example, a copper sprayed film).

FIG. 4 shows a sectional view of a conventional method for manufacturing a thermal sprayed substrate.
This manufacturing method first involves (1) forming a metal substrate 1 by pressing a metal material with good heat dissipation, such as aluminum or copper-based metal (
Figure 4(a)).

(2) One side of the metal substrate 1 is roughened by sandblasting as a pretreatment for thermal spraying in order to better cover the bond with the thermal sprayed film (FIG. 4(b)). Metal substrate 1 by sandblasting
produces a convex warp d.

(3) Apply a metal mask such as iron to the metal substrate 1 and spray semilac or copper to form a predetermined circuit pattern (fourth
Figure (C)).

[Problems with Background Art] This thermal sprayed substrate is mounted with semiconductors and the like and then used by being tightly fixed to a heat dissipation plate (radiation fin) 10 (see FIG. 3) with screws or the like. The surface of the sprayed substrate and the surface of the heat sink must be in perfect contact with each other to improve heat conduction, and for this reason, it is required that the surfaces have good flatness when mounting the sprayed substrate. A major problem with conventional manufacturing methods is that this flatness cannot be achieved. The reason why the flatness of the thermal sprayed substrate cannot be obtained is that warpage occurs due to the sandblasting treatment performed as a pretreatment for thermal spraying. This amount of warpage (Fig. 4 (b)
The size of d) shown in Figure 1 varies depending on the size of the board, the thickness of the board, and the intensity of sandblasting. For example, the length of the sprayed board is 7 cm.
, an aluminum plate with a width of 4 cm and a thickness of 1.5 mm causes a warpage amount of approximately 0.1 to 0.3 mm. Furthermore, if an external force is applied to the sprayed substrate to correct the warpage that has occurred, defects such as cracks in the semilac film will occur.

[Object of the Invention] It is an object of the present invention to provide a method for manufacturing a thermal sprayed substrate that solves the above-mentioned problems and has a good flatness of the mounting surface.

[Summary of the Invention] In order to strengthen the bond between the substrate and the sprayed film in the production of a thermally sprayed substrate, it is necessary to roughen the surface of the substrate to be thermally sprayed by sandblasting in advance.

However, this sandblasting causes the surface to curve into a convex shape. In the present invention, a concave warp is given to the metal substrate in advance before the sandblasting process so that a flat surface can be obtained by the sandblasting process.

That is, the present invention is a method for manufacturing a thermal sprayed substrate having a single thermal sprayed surface, in which a metal substrate is manufactured by press punching, and then a concave (0, 05 to 1.00) IIIIIIl warpage is applied, and then the concave opposite substrate surface is subjected to a sindblasting treatment, and then an insulating material or metal is thermally sprayed on the opposite substrate surface to form a predetermined pattern. This is a method for manufacturing a thermal sprayed substrate.

When a metal substrate is manufactured by press punching, the periphery of the pressurized metal substrate sag downward from the substrate surface, and a so-called burr occurs on the opposite substrate surface.

In order to improve the adhesion with the heat sink, the sloping side of the metal board should be attached to the heat sink, and the opposite side should be the sprayed surface (
(sandblast surface). Also, claim 1
The warpage described in Section 1 is a chord (line segment) that connects both ends of the board from a point on the board surface in a cross-sectional figure such as the longitudinal direction of the metal board (referred to as the X-X axis) or the width direction (Y-Y axis). This is the maximum vertical distance that can be reached.

For example, the distance indicated by d in FIGS. 1 and 4 is the curvature. It is effective whether the warp is applied in one direction along the x-X axis or in a so-called spherical shape in two directions, the X-x and Y-Y axes. The amount of warpage given to the metal substrate in advance varies depending on the size of the substrate, the thickness of the substrate, the intensity of sandblasting, etc. The range of warpage (0.05 to 1.00 mm) was determined through trials in consideration of the dimensional structure of the thermally sprayed substrate to be used and the sandblasting treatment conditions. Warpage amount 0.05
WIII1 is insufficient to compensate for warping caused by sandblasting, and 1.00mff1 or more is inappropriate because warpage remains after sandblasting.

[Embodiment of the Invention Figures 1 (a) to C) show an embodiment of the manufacturing method of the present invention with cross-sectional views, and Figure 2 (a)
) and (b) are a plan view and a side view, respectively, of a thermal sprayed substrate manufactured according to the present invention. Thickness 1.5m+
A metal substrate 1 having mounting holes 4 and having a length of 7 cm and a width of 4 cm is made by ordinary press punching from a No. n aluminum plate. When mounting this board, the board surface (bottom surface in Figure 1) of the sag 11 formed by press punching is made a surface for mounting with the heat sink, so that "burrs" during pressing do not impede the adhesion of the mounting. The substrate surface opposite to the droop side substrate surface (top surface in Fig. 1) is the sprayed surface.Next, warp ld of about 0.15 mm (Fig. 1) so that the sprayed surface of the substrate 1 has a concave shape. The method for imparting warpage is not particularly limited, but in this example, a mold was used to forcibly impart warpage. FIG. Next, the entire surface of the sprayed surface is roughened by the usual υ-nd blasting method (for example, air pressure 5 kG/c...2, sand particle mesh #80).The sprayed surface changes into a convex shape by sandblasting, but as mentioned above. Since the concave warpage is provided in advance, the metal substrate 1 after sandblasting has almost no warpage and has good flatness.

FIG. 1(b) shows a cross section of the substrate 1 in this state.

Next, alumina ceramic is partially sprayed using a plasma spraying device to form an insulating layer 2, and then copper is coated on the surface of the insulating layer 2 and the metal on which the ceramic is not sprayed, in order to facilitate soldering of semiconductor elements. Thermal spraying is performed on the substrate surface to form a thermally sprayed film. The thickness of the sprayed coating is about (0.15 to 0.20) mm for the alumina ceramic coating 2 and about (0.10 to 0.15) mm for the sprayed copper coating 3. Figure 3 shows a semiconductor device (commonly called RA) for rectifying three-phase AC voltage used in automobiles.
Here is an example of its usage. In the figure, 7 is a semiconductor lead;
8 is a semiconductor element, which is coated with a copper sprayed film 3 on a sprayed substrate by solder 9.
is fixed to. The thermal sprayed substrate on which the case 6, semiconductor element 8, etc. are mounted is attached with bolts 5 so as to be in close contact with the heat sink (radiating fins>10).

[Effects of the invention] When using an aluminum plate with a size of 7 cm x 4 cm and a thickness of 1.5 mm as the metal substrate of the thermal sprayed substrate, the conventional manufacturing method left about 0.15 m111 of warped pieces on the board, but about In the manufacturing method of the present invention, which gives a warpage of 0.15 mm, the amount of warpage is 0.06 mm or less, and a thermal sprayed substrate with good flatness and good thermal conductivity can be obtained.

[Brief explanation of the drawing]

Fig. 1 (A > C) is for explaining the manufacturing method and its steps of the present invention, and shows the results of the manufacturing method of the present invention and its steps, respectively. The cross-sectional views, FIGS. 2(a) and <b>, are
Plan and side views of thermal sprayed substrates manufactured by the present invention or conventional manufacturing methods, FIGS. 3(a) and (b)
Figures 4(a) to 4(c) are a plan view and a cross-sectional view of a three-phase AC rectifier for an automobile showing an example of mounting a thermal sprayed board, and Figures 4(a) to 4(c) are for explaining the conventional manufacturing method and its process, and are respectively press punched. FIG. 3 is a cross-sectional view of a metal substrate or a thermal spray substrate after sandblasting and after forming a thermal spray film. 1... Metal substrate (aluminum plate), 2... Insulating sprayed film (ceramic sprayed film), 3... Metal sprayed film (copper sprayed film), 11... Drop, △... Thermal sprayed substrate , d...Amount of warpage. Patent applicant: Toshiba Corporation Figure 1 Figure 2

Claims (1)

[Claims] 1 A method for manufacturing a thermal sprayed substrate with a single thermal sprayed surface, in which a metal substrate is manufactured by press punching, and then a concave (0.
A thermal sprayed substrate characterized in that a warp of 0.05 to 1.00 mm is applied, and then the opposite substrate surface is sandblasted, and then an insulator or metal is thermally sprayed on the opposite substrate surface to form a predetermined pattern. manufacturing method.