JPS60130192A - Method of producing semiconductor metallizing board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] - The present invention relates to a method for manufacturing a circuit board on which a semiconductor element is mounted, and more specifically, a method for manufacturing a circuit board on which a semiconductor element is mounted. The present invention relates to a thermal spray masking process used when forming a copper layer pattern on a substrate.

[Technical background of the invention]

Typical circuit boards equipped with 11′ conductor elements include:
There is a circuit board for high heat dissipation formed on a metal heat sink.

In such a circuit board, a semiconductor element is mounted on a metal heat dissipation plate via a surface or a ceramic insulating plate, and a bonding pad is arranged via the ceramic insulating plate, and therefore has high heat dissipation efficiency. Low costs are required from both parts and process perspectives.

Conventional circuit boards for high heat dissipation have the following structure: ■A structure in which a metal heat sink, a ceramic insulating plate, and a metal plate for bonding pads are assembled; ■A ceramic insulating plate with a thick plating layer formed as a bonding pad and a metal heat sink are assembled. structure has been commonly used.

The first sectional view and the second sectional view illustrate the conventional structure (2). In the same figure, 1 is a copper-based heat sink, 2
is a semiconductor element, 6 is a bonding pad, 4 is a thin metal wire connecting the electrode of the semiconductor element 2 and the bonding pad,
5 is Al that insulates the bonding pad 4 and the heat sink 1.
It is a ceramic insulating board such as 2O3.

To assemble the circuit board shown in Figure 1.2, insulating plate 5
0 Apply a mask jig to both sides and evaporate a conductive material such as copper, or apply and bake a paste such as Ag, Pt, W, Mo, etc.
A metallized layer was formed in advance, and nickel plating was applied to the copper plate surfaces of the heat dissipating plate 1 and the bonding pad B, and my father used silver brazing 6 for soldering.

Next, the conventional structure (2) is an insulating plate and a heat sink, in which a metallized layer is formed on the insulating plate 5 as in (2), and then a thick conductive metal layer is formed on the metallized layer by electrolytic or electroless plating. This is a circuit board assembled using solder or silver solder as in ■.

[Problems with background technology]

The above conventional circuit board for high heat dissipation has the following problems.

(1) In order to assemble the conventional structure board of (■), metallization processing is performed on both sides of the insulating plate by vapor deposition and paste printing.
[Additional] As the number of pastes increases, paste becomes expensive,
This is an obstacle to cost reduction.

(11) In the conventional structure board of ■, the copper plate for the bonding pad is not necessary, but the plating method for forming the bonding pad is a wet process, which complicates the process and requires post-treatment to make the plating solution pollution-free. becomes. Furthermore, it takes a long time to thicken the plating layer as a pad, the dimensions of some corners and edges are inaccurate, and the adhesion of the twinkling layer is low, so the pad is likely to peel off.

(III) In the case of a circuit configuration in which it is necessary to insulate a semiconductor element by cutting it into a heat sink, the semiconductor element is mounted on the heat sink through an insulating plate, similar to a bonding pad, to reduce the heat generated by the element. Dissipation is likely to be impaired.

■Since an insulating plate is used, two layers of solder must be applied between the heat dissipation plate and the insulating plate and between the insulating plate and the bonding pad, so there are many bonding steps.

As mentioned above, circuit boards with conventional structures have various problems, but if an insulating layer or metal layer is formed by thermal spraying, the number of bonding steps can be reduced, and the thickness of the insulating layer or metal layer can be reduced. It is thought that it is possible to do so. However, selectively forming a pattern by thermal spraying has not been put to practical use in the past, and only thermal spraying over the entire surface has been performed. The reason for this is that there are two methods: printing resist ink as a mask for thermal spraying and spraying by applying a metal plate mask, but the former requires wet processing to remove the resist ink, and the latter ( l-j: This is because if the mask is used 3 to 5 times, the sprayed layer will accumulate on the mask, making it unusable and making the mask expensive.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a thermal sprayed substrate using a mask in which a thermal sprayed layer is not deposited and stuck when manufacturing a circuit board for mounting a semiconductor element by a thermal spraying method. Another object is to provide a method for manufacturing a circuit board that has high heat dissipation efficiency and is low cost in terms of both components and processes.

[Summary of the invention - Cao]

This invention uses tetrafluoroethylene resin (
By using a mask coated with Teflon, no thermal spray layer is deposited or stuck on the mask, and therefore a thermal spray pattern can be selectively formed on the substrate in a practical manner. Furthermore, since it has become possible to form thermal spray patterns on the substrate, insulating layers and conductive metal layers can be formed as thin as necessary, and the number of parts and bonding processes can be omitted, resulting in high heat dissipation efficiency and low heat dissipation. A low cost circuit board is obtained.

[Embodiments of the invention]

A plan view of the plate, and FIG. 4 is a sectional view thereof.

Referring to Figures 6 and 4, 1 is an aluminum heat sink, 65 is a thermally sprayed A1. ,．． 03 insulation layer, 66 thermally sprayed copper (
Cu) layer, 66a is a thermally sprayed C layer that becomes a bonding pad.
The u layer 53b is a sprayed Cu layer on which the semiconductor element 2 is mounted.

Figures 5 and 6 are AI. Mask 5 for o3 thermal spraying
0, FIGS. 7 and 8 are masks 70 for CLI thermal spraying. 5 and 7 are partial plan views, and FIGS. 6 and 8 are sectional views of FIGS. 5 and 7, respectively. In both of the masks shown in FIGS. 5 to 8, a patterned hole 12 is formed in a 1 mm thick iron plate 11, and the surface of the iron plate 11 is subjected to a blast treatment to have a surface roughness of 12 to 25 μm in advance. Next, the entire surface of the firing material is coated with a Teflon layer 16 having a thickness of about 25 to 50 μm. A step 14 corresponding to the already formed A1°03 layer 65 is formed on the lower surface of a mask 70 for Cu thermal spraying used in a step after A1□03 thermal spraying.

Next, the Δ1□O3 thermal spraying process will be explained with reference to FIG.
The sprayed bonding surface of the M-thick aluminum heat sink 1 is blasted with No. 80 mesh/yu Al2O3 grains to a surface roughness of about 25μ, and the heat sink 1 is arranged on the jig 91, A1□03 The thermal spray mask 50 is applied and fixed with jig fixing bolts 92. A
When l2O3 is sprayed by plasma spraying, a mask 50 is formed.
I7) A1201 that hit the Teflon layer 16. Thermal spray particles 96 do not accumulate on the Teflon layer but slide away, but are deposited 94 on the heat sink. The thickness of the Al2O3 layer is approximately 0.15 to 0.02 mm.

Next, the C1l thermal spraying process will be explained with reference to FIG.
The heat dissipation plates 1 on which the 2O3 layer 65 has been formed are arranged on the jig 91, and the jig fixing bolts 9 are attached to the CLI thermal spray mask.
Fix it at 2. When Cu is thermally sprayed, Cu is not deposited on the mask because of the Teflon layer 16, but is deposited 94 on the Al2O3 layer 35 and the heat sink 1.

The material of the substrate 11, which is the core of the mask, is not limited as long as it can be baked with Teflon, but a steel plate is preferable in terms of heat deformation. -It is far superior to other fluororesins such as hexafluorinated propylene copolymer resin in that it does not cause thermal spray particles to stick to it.

As an example of a high temperature dissipation substrate manufactured according to the present invention,
The A1203 insulating layer and the sprayed C11 layer can be formed on the part where the semiconductor element 2 is mounted in FIG. 6, as well as the part directly under the bonding pad 65, to make a fully insulating type substrate. In this case, if there is no problem, the Al2O3 layer may be thermally sprayed over the entire surface of the heat sink without using a mask, and only the Cu layer may be patterned using a mask.

In addition, in the above-mentioned fully insulated substrate, the sprayed Cu layers are on the same level, so the sprayed edges are relatively rough (80
~100μ) Surface roughness can be improved by polishing the copper pattern surface. Direct wire bonding is also possible if the surface roughness is 6 to 12μ.

When polishing, a 00 layer of about 200 μm is required.

The circuit board is not limited to one formed on a metal heat sink, but may also be one in which only the C1l pattern for an integrated circuit is formed on a ceramic substrate by the masking method of the present invention. This is because the feature of this invention lies in the thermal spray mask.

〔Effect of the invention〕

Compared to the conventional method of manufacturing a circuit board using the DEFRON coat mask of this invention, which forms a meklyz layer or a plating layer on the surface of a ceramic or insulating board, it is possible to directly form a circuit board on the surface of an insulating layer and a copper layer. Since patterns or laminated patterns can be created by thermal spraying, the number of parts and the number of steps involved in pasting are greatly reduced, dramatically reducing assembly costs.

Since the warped insulating layer is formed by thermal spraying, the thickness of conventional ceramic insulating plates could not be reduced to less than 0.4 to 0.6 mm, but it can be reduced to about 0.15 to 0.2 mm, making it possible to reduce the thickness of semiconductor devices. If the insulating layer immediately below is made thin like this, a circuit board with extremely high heat dissipation efficiency can be obtained.

In short, the reason why a low-cost circuit board with high heat dissipation efficiency can be obtained is that by applying a Teflon coat to the thermal spray mask, the thermal spray particles are not deposited on the Teflon layer. can be easily removed, and the lifespan of conventional masks is 10 times longer than the 3 to 5 times used.
This is due to the fact that it extends more than twice as long.

[Brief explanation of drawings]

Figure 1 is a plan view of an element-mounted circuit board manufactured using a conventional manufacturing method.
2 is a sectional view taken along the line 11-■ in FIG. 1, FIG. 6 is a plan view of a circuit board produced by the manufacturing method of the present invention, and FIG.
5 and 7 are partial plan views of the thermal spray mask, and FIGS. 6 and 8 are respectively 5
Figure Vl - Cross-sectional view along Vl i and Figure 7 Vl11-■
FIG. 9 is a sectional view taken along line 1, and a sectional view illustrating a 10P thermal spraying process. 1... Substrate, 65... Alumina layer, 33a, 33b
...Copper layer, 2...Semiconductor element, 50, 70...
Thermal spray mask, 16...Tetrafluoroethylene resin coating. Figure 1 #1.2

Claims (1)

[Claims] 1. When manufacturing a circuit board on which a semiconductor element is mounted by forming an alumina layer or a copper layer on a substrate by a thermal spraying method, thermal spraying is performed using a thermal spray mask coated with tetrafluoroethylene resin (t!J). A manufacturing method for thermal sprayed substrates for semiconductors.