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US 4,959,119 AGranted
Method for forming through holes in a polyimide substrate
AssigneeE. I. Du Pont de Nemours and Company
InventorThomas D. Lantzer
Life of this patent
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Abstract
Hole formation in a polyimide substrate employs a carbon dioxide laser.
Claims2
A method of forming at least one through hole with an electrically conductive wall in a polyimide substrate to connect electrically conductive surface portions on opposite sides of the substrate with an initial step of forming at least one hole in the substrate by employment of a carbon dioxide laser for polyimide removal wherein
- (a) the carbon dioxide laser is employed at an average energy density in a range of from 18,000 to 45,000 watts per square inch,
- (b) a predominant oxygen containing atmosphere is present,
- (c) a carbon dioxide laser beam is defocussed in polyimide removal,
- (d) a portion of the carbon dioxide beam passes through the polyimide substrate prior to complete hole formation onto a reflective surface which deflects at least 70% of the beam striking the reflective surface into the polyimide substrate to aid in hole formation, and
- (e) relative motion is present between the laser source and the polyimide substrate for at least a portion of the hole formation.
2 more elements
Dependencies are inferred from the claim text.