Etching solution for forming an embedded resistor
AssigneeGould Electronics Inc.
InventorsDan Lillie, Jiangtao Wang
Life of this patent
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Abstract
A resistive etching solution containing thiourea, which is particularly suitable for etching an electrically resistive material comprised of a nickel-chromium alloy. The resistive etching solution allows for fast and effective etching of a nickel-chromium alloy in cases where the ratio of (a) copper surface area to (b) nickel/chromium surface area, is relatively large, and where fine feature etching is desired.
Claims31
An etching solution for etching an electrically resistive material including a nickel-chromium alloy, comprising:
- hydrochloric acid;
- and
- thiourea.
A process for forming an embedded resistor from a resistive foil having a copper layer and a resistive layer, wherein the resistive foil is bonded to a dielectric layer, the method comprising:
- selectively removing portions of the copper layer with a copper etchant to form trace lines;
- and
- selectively etching the resistive layer with an etchant comprised of hydrochloric acid and thiourea.
Dependencies are inferred from the claim text.