Methods of and apparatus for forming conductive patterns on a substrate
OwnerPeter L. Moraninventor
Life of this patent
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Abstract
A method of forming an electrically conductive pattern on a substrate includes the steps of forming a layer of gold on an electrically insulating substrate and coating the gold layer with a photo-resist. The resist is exposed to light through a photo mask and the exposed portions of the photo-resist are selectively removed by etching. The now exposed parts of the gold layer are coated with copper and the remaining photo-resist is removed. The exposed parts of the gold layer and the copper are subjected to molten tin which simultaneously acts to dissolve the exposed parts of the gold layer and to form an electrically conductive coating on the copper. The process enables the formation of a precise conductive pattern with enhanced reliability.
Claims20
A method of forming a conductive pattern on a substrate comprising:
- the steps of coating the substrate with a first electrically conductive material, to form a first layer;
- forming a resist pattern on the first layer;
- depositing a second electrically conductive material on the parts of the first layer not covered by the resist pattern;
- removing the resist pattern, and
- temporarily subjecting the now exposed parts of the first layer and the deposits of said second conductive material with a third electrically conductive material in its molten state, the third electrically conductive material being such that when in its molten state it acts simultaneously to dissolve the first conductive material and to provide a coating on said second electrically conductive material.
A method of forming an electrically conductive pattern on a substrate comprising the steps of:
- forming a layer of gold or silver on an electrically insulating substrate;
- coating said gold or silver layer with a photo-resist;
- exposing the photo-resist to light through a photo mask;
- selectively removing the exposed portions of the photo-resist;
- coating the now exposed parts of the gold or silver layer with a second electrically conductive material other than gold or silver;
- removing the remaining photo-resist, and
- subjecting the exposed parts of the gold or silver layer and the said second electrically conductive material to a third electrically conductive material in molten form, the third electrically conductive material being such that it simultaneously acts to dissolve the exposed parts of the gold or silver layer and form an electrically conductive coating on the second electrically conductive material.
Apparatus for treating a substrate carrying an electrically conductive pattern comprising:
- a container for containing an oxidation inhibiting vapourisable liquid;
- heating means for heating the container to a level at which the liquid therein vapourises;
- a vessel for holding a molten electrically conductive material;
- means supporting the vessel in the container to be above the liquid phase of the vapourisable liquid, and
- means for displacing said substrate along a predetermined path through the container to the vessel, whereby when the heater is operative it will cause the vapourisable liquid to vapourise and the vapour to heat the material in the vessel to its molten state, and to form a preheating oxidation inhibiting environment around the said path.
A circuit comprising an electrically insulating substrate and an electrically conductive pattern carried by the substrate characterized in that the pattern comprises:
- a first electrically conductive material forming a first layer on the substrate,
- a second electrically conductive material forming a second layer on the first layer, and
- a coating of a third electrically conductive material on the second layer;
- the third electrically conductive material, when in its molten state, being capable of coating the second material and dissolving the first material.
Dependencies are inferred from the claim text.