THICK FILM CIRCUIT DEVICE CONTAINING CERAMIC SUBSTRATE

Japanese Patent JPS62185398

A

The invention relates to a thick-film circuit arrangement having an electronic circuit which is constructed on a surface (17) of a ceramic substrate plate (3) and which consists of conductor paths (5), resistors, capacitors and components, in particular integrated switching circuits without a housing, formed according to thick-film technique. This structure has between the electrically conductive structures (5) a sintered, nonconductive paste substantially filling the intermediate spaces between them and both the structures and the interposed pastes are covered by a sintered insulating paste. For concealing the thick-film circuit arrangement from unauthorized access, the following covering construction is carried out: 1. the paste in the intermediate spaces fills the same between the electrically active thick-film conductor structures in such a manner that the tops of the electrically active structures and the insulating filling layer (7) formed from an insulating paste and filling the intermediate spaces between them are situated substantially in one plane, and 2. the insulating paste is provided over the combined conductor/filling layer (11) in a covering and smoothing manner to form at least one insulating first thick-film anti-access layer (13) which, by additional observation-impeding inclusions (dyes, particles) impedes an optical recognition of the underlying structures, especially when the first thick-film anti-access layer or layers is or are not succeeded by further anti-access layers.

BUORUFUGANGU SHIYUNITSUTOKAA
MIKAERU NOOBUAA
KAI APERU

JP1630887A

August 13, 1987

January 28, 1987

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PHILIPS NV

H01L21/70; H05K3/46; H01L25/16; H01L27/01; H05K3/28; H05K1/09; H05K1/16; (IPC1-7): H05K3/46

JP58092763B
JPS60216599A	1985-10-30
JPS52117169A	1977-10-01
JP59191794B

Akihide Sugimura

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