Method for producing waveguide substrate

Abstract

To allow a metal film to have a sufficient thickness around a bottom surface of a non-through hole and prevent the metal film from being peeled from a substrate surface, a method for producing a waveguide substrate includes forming a first metal film on (i) a first main surface of a substrate, at which first main surface a non-through hole opens, and on (ii) an inner wall of the non-through hole, forming resist on a first main surface side of the substrate in such a manner that the resist blocks the opening of the non-through hole, removing a first portion of the first metal film which first portion is on the first main surface, removing the resist, and forming a second metal film on the first main surface of the substrate in a state where the first metal film is present on the inner wall of the non-through hole.

Description

technical field [0001] The present invention relates to a method of manufacturing a waveguide substrate. Background technique [0002] A millimeter-wave communication module using a post-wall waveguide (hereinafter sometimes referred to as “PWW”) is known as a method for realizing an inexpensive and small millimeter-wave communication module (for example, refer to Patent Document 1). [0003] This PWW is a waveguide as follows: a printed circuit board with a ground conductor formed on the surface and the back surface, and a plurality of column walls that stand up between the ground conductor layers, that is, conductor columns, are arranged. The conductor columns are equivalent to conventional waveguides. metal side walls. In the above-mentioned millimeter wave communication module, the wireless communication IC mounted on the substrate of the PWW is connected to the transmission line (microstrip line, coplanar line, strip line, etc.) by wire bonding, bump connection, etc. ...

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Problems solved by technology

[0006] However, when the non-through hole forming the conductor pin has a small diameter and a high aspect ratio, for example, the hole diameter is 100 μm or less, and the depth is about 460 μm, it is difficult for the plating solution to reach the bottom surface of the non-through hole, so a sufficient coating cannot be ensured near the bottom surface. Impedance matching is not possible due to thick metal film

[0007] In addition, if the metal film thickness is ensured only by sputtering near the bottom surface of the non-through hole without plating, the film thickness of the metal film for ground conductor formed on the surface of the substrate becomes thicker than necessary. There is a problem that the metal film is easily peeled off from the substrate due to the difference in expansion coefficient between the metal film and the substrate

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