PURPOSE: To manufacture even a printed board having a high aspect ratio by using negative photoresist by exposing the photoresist formed on the surface of an inner wall of a through hole with suitable exposure amount, and allowing the resist of a predetermined thickness or more to remain on the entire surface of the inner wall of the hole after a developing step is finished.
CONSTITUTION: Negative photoresist is formed on a surface of an inner wall of a through hole of a board having a copper-plated through hole and the surface of the board by electrodeposition. Its exposure amount is suppressed to a range of 30-300mJ/cm2 irrespective of whether the photoresist in the hole is exposed or not to be exposed. Even after an unexposed part of the surface of the board is completely developed, the resist of 0.5μm or more remains on the entire surface of the inner wall of the hole. Thus, copper of the inner wall of the hole can be protected without etching in an etching step, the exposure amount may be reduced, and a resist pattern having high resolution can be formed.
UEHARA HIDEAKI
AMANOKURA HITOSHI
KATO TAKURO
TSUKADA KATSUSHIGE
YAMAZAKI YUJI
YAMADA MASAHARU
SHIOTANI TOSHIHIKO
NAGASHIMA YOSHIHISA
HITACHI CHEMICAL CO LTD
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