JPH05243729A - Manufacture of through-hole wiring board - Google Patents

Abstract

PURPOSE:To prevent a metal film from melting at the edge part of a through hole in an etching process by sticking a first sheet to a first principal plane, when a resist is given to a second principal plane, by closing one end face of the through hole and by positioning the closed end face down. CONSTITUTION:A first sheet 16 is stuck to a first principal plane 12. The first sheet 16 closes one end face of a through hole 11. Next, after a second principal plane 13 is directed upward and a resist 17 is given to the second principal plane 13 and the inner peripheral face of the through hole 11, the resist 17 is dried and the first sheet 16 is separated from the first principal plane 12. Subsequently, a second sheet 18 is stuck to the second principal plane 13 via the resist 17. Thereafter, the first principal plane 12 is directed upward and a resist 19 is given to the first principal plane 12 and the inner peripheral face of the through hole 11. Then, after the resist 19 is exposed and developed, the resists 17, 19 are subjected to post baking. After that, the resists 17, 18 are removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a through-hole wiring board having a wiring conductor made of a patterned metal thin film.

[0002]

2. Description of the Related Art This kind of through hole wiring board is used, for example, in a microwave strip line element. In this microwave stripline device, a patterned metal thin film is formed on one main surface of the substrate,
On the other main surface, a metal thin film is formed over the entire surface to serve as a ground conductor. Photolithography is generally used to pattern a metal thin film on one main surface of a substrate.

A conventional method for manufacturing a through-hole wiring board will be described with reference to FIG. First, as shown in FIG. 2A, a substrate 5 having a through hole 1 and a metal thin film 4 formed on both main surfaces 2 and 3 and an inner peripheral surface of the through hole 1 is prepared.

Next, as shown in FIG. 2B, a resist 6 is applied to both main surfaces 2 and 3 of the substrate 5 and the inner peripheral surface of the through hole 1 so as to cover the metal thin film 4. The application of the resist 6 is performed by immersing the substrate 5 in a resist bath or using a roll coater.

Next, as shown in FIG. 2C, the resist 6 on the first main surface 2 of the substrate 5 is exposed and developed to obtain a part of the resist 6. Are removed according to the pattern.

Next, as shown in FIG. 2D, the substrate 5
The metal thin film 4 on the first main surface 2 of the is etched, and the metal thin film 4 is formed according to the pattern of the resist 6.
Is patterned.

Thereafter, although not shown, the remaining resist 6
Are removed. In this way, the first major surface 2 of the substrate 5 is
A patterned metal thin film 4 is formed thereon, and on the second main surface 3 of the substrate 5, all the metal thin films 4 are left and formed on these first and second main surfaces 2 and 3, respectively. The metal thin film 4 formed is the metal thin film 4 in the through hole 1.
A through-hole wiring board electrically connected by is obtained.

[0008]

However, in the step of FIG. 2 (b) described above, the resist 6 can be formed with a uniform film thickness in the portion where the through hole 1 is not formed. At the edge portion of the through hole 1, the thickness thereof may be thin, or in extreme cases, the metal thin film 4 may be exposed.
FIG. 2B and the following (c) and (d) show a situation in which such an inconvenience occurs.

As described above, when the resist 6 does not have a sufficient film thickness at the edge portion of the through hole 1, in the step of FIG.
Undesirably, the edge portion of the through hole 1 may be etched, which may cause peeling or loss of the metal thin film 4 and increase the resistance of electrical conduction through the through hole 1. However, there is a problem in that the electrical characteristics are deteriorated or the electrical conduction through the through hole 1 is cut off.

Therefore, an object of the present invention is to provide a method of manufacturing a through-hole wiring board which can solve the above-mentioned problems.

[0011]

The present invention is characterized by the following steps in order to solve the above-mentioned technical problems.

First, there is prepared a substrate having through holes and a metal thin film formed on both main surfaces and the inner peripheral surfaces of the through holes. Then, on the first main surface of the substrate, a first
Sheet is pasted. Next, with the second main surface of the substrate facing upward, a resist is applied to the second main surface and the inner peripheral surface of the through hole. Then, the first sheet is peeled off from the first main surface, and the second sheet is attached to the second main surface of the substrate via the resist. Next, a resist is applied to the first main surface of the substrate and the inner peripheral surface of the through hole. In this way, after the resist is applied, the resist on the first main surface of the substrate is removed according to the pattern to be obtained, and the metal thin film on the first main surface of the substrate is patterned by etching. It

[0013]

In the present invention, when resist is applied to the second main surface, the first sheet is attached to the first main surface, one end surface of the through hole is closed, and the closed end surface is moved downward. Since it is positioned, the resist is in a state of collecting on the end face of the through hole closed by the first sheet. Therefore, the resist is formed with a sufficient thickness at the edge portion of the through hole on the first main surface side. The second main surface side is covered with the second sheet during etching.

[0014]

According to the present invention, therefore, the metal thin film is sufficiently protected by the resist and the second sheet at the edge portion of the through hole, so that the metal thin film is melted at the edge portion of the through hole in the etching process. Never. As a result, the metal thin film does not undesirably peel off or become defective,
In electrical conduction through the through-hole, disconnection and increase of resistance value are prevented, the performance of the obtained through-hole wiring board is improved and stabilized, and the yield of manufacturing the through-hole wiring board is improved. Can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an embodiment of the present invention.

First, as shown in FIG. 1A, a substrate 15 having a through hole 11 and a metal thin film 14 formed on both main surfaces 12 and 13 and an inner peripheral surface of the through hole 11 is prepared. . This substrate 15 is the same as that shown in FIG.
It has the same structure as the conventional substrate 5 shown in FIG. The substrate 15 is made of alumina, for example, and the metal thin film 14 is made of gold, for example.

Next, as shown in FIG. 1B, the substrate 15
The first sheet 16 is attached to the first main surface 12 of the. An adhesive sheet is preferably used for the first sheet 16. Instead of the adhesive sheet, the first sheet 16 may be attached to the substrate 15 with an adhesive prepared separately. The first sheet 16 has one end surface of the through hole 11 closed.

Next, as shown in FIG. 1C, the substrate 15
The second main surface 13 of the
A resist 17 is applied to the inner peripheral surface of the through hole 11. A spin coater is advantageously used to apply the resist 17. After the resist 17 is applied, the resist 17 is naturally dried or oven dried at a low temperature of 50 to 70 ° C. As a result, the adhesion between the substrate 15 and the resist 17 is increased, and the resist 17 is prevented from being peeled off by the first sheet 16 when the first sheet 16 is peeled off later. If a heat-resistant material is used as the first sheet 16,
The resist 16 can be pre-baked at a temperature of 80 to 100 ° C.

Next, as shown in FIG. 1D, the first sheet 16 is peeled from the first main surface 12 of the substrate 15.

Then, as shown in FIG. 1 (e), the substrate 1
The second sheet 18 is attached to the second main surface 13 of No. 5 via the resist 17. Either of the step of peeling the first sheet 16 shown in FIG. 1D and the step of sticking the second sheet 18 shown in FIG. 1E may be performed first. The second sheet 18 is also preferably made of an adhesive sheet.

Next, as also shown in FIG. 1 (e), preferably, the first main surface 12 of the substrate 15 is directed upward, and the first main surface 12 and the inner peripheral surfaces of the through holes 11 are formed. Resist 19 is applied. A spin coater is advantageously used to apply the resist 19, as in the case of the resist 17 described above. Further, the applied resist 19 is dried similarly to the resist 17.

Next, as shown in FIG. 1 (f), the substrate 15
The resist 19 on the first main surface 12 is exposed and developed, and the resist 19 is removed according to the pattern to be obtained. After that, the resists 17 and 19 are post-baked. As the second sheet 18, it is preferable to use a sheet having heat resistance to withstand such post baking.

Next, as shown in FIG.
Etching is applied to the metal thin film 14 on the first main surface 12 of and the resist 19 is patterned according to the pattern of the resist 19. At this time, since the second sheet 18 is attached to the second main surface 13 side of the substrate 15, the second main surface 13 side is perfectly protected against the etchant.

Next, although not shown, the second sheet 18
Is removed and the resists 17 and 18 are removed.

In this way, the metal thin film 14 becomes the substrate 1
5 is patterned on the first main surface 12 side and remains on the entire second main surface 13 side.
A through-hole wiring board in which 4 is electrically connected by the metal thin film 14 in the through-hole 11 is obtained.

If the second sheet 18 attached in the step of FIG. 1 (e) does not have heat resistance, the second sheet 18 in the step of FIG. 1 (f) is post-baked. The sheet 18 may be peeled off, and the second sheet 18 may be attached again in the step of FIG.

Further, in the above-mentioned embodiment, the metal thin film 14 is used.
The portion formed on the side of the second main surface 13 of the above was left entirely so as to function as a ground conductor. The metal thin film 14 is also patterned on the side of the second main surface 13 as described above. Good.

[Brief description of drawings]

FIG. 1 is a sectional view sequentially showing steps included in one embodiment of the present invention.

2A to 2D are cross-sectional views sequentially showing steps included in a conventional method of manufacturing a through-hole wiring board.

[Explanation of symbols]

 11 Through Hole 12 First Main Surface 13 Second Main Surface 14 Metal Thin Film 15 Substrate 16 First Sheet 17, 19 Resist 18 Second Sheet

Claims (1)

[Claims] 1. A substrate having a through hole and a metal thin film formed on both main surfaces and an inner peripheral surface of the through hole is prepared, and a first sheet is attached to a first main surface of the substrate, With the second main surface of the substrate facing upward, a resist is applied to the second main surface and the inner peripheral surface of the through hole, the first sheet is peeled from the first main surface, and the substrate On the second main surface of the
A sheet is applied, resist is applied to the first main surface of the substrate and the inner peripheral surface of the through hole, and the resist on the first main surface of the substrate is removed according to the pattern to be obtained, A method of manufacturing a through-hole wiring board, comprising the steps of patterning a metal thin film on the first main surface of the board by etching.