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Maskless Circuit Board Patterning Using Scanning Lasers

IP.com Disclosure Number: IPCOM000039574D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Onoda, GY: AUTHOR [+2]

Abstract

There is a pressing desire to do away with standard lithography-mask technology for making circuitization patterns on boards. The cost of masks and photoresist together with alignment problems associated with masks makes it important to find suitable alternatives. The following techniques will permit rapid patterning of epoxy boards, fully covered with 1.25 mil copper, to become circuitized by subtractive etching using coating schemes. The coating is selectively removed via a scanning laser which can be programmed via a computer and microprocessor in conjunction with a similarly controlled automated table. Patterning occurs by local removal of the coating via heat with the laser providing the energy to boil, sublimate or decompose the coating. Photothermal decomposition is also a viable process.

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Maskless Circuit Board Patterning Using Scanning Lasers

There is a pressing desire to do away with standard lithography-mask technology for making circuitization patterns on boards. The cost of masks and photoresist together with alignment problems associated with masks makes it important to find suitable alternatives. The following techniques will permit rapid patterning of epoxy boards, fully covered with 1.25 mil copper, to become circuitized by subtractive etching using coating schemes. The coating is selectively removed via a scanning laser which can be programmed via a computer and microprocessor in conjunction with a similarly controlled automated table. Patterning occurs by local removal of the coating via heat with the laser providing the energy to boil, sublimate or decompose the coating. Photothermal decomposition is also a viable process. A number of substances can be used to act as an inexpensive coating: glass or TEFLON* beads (micron sized) which might be fused onto the substrate, very dilute photoresist, or waxes, such as paraffin. Both the thinned photoresist and wax can be applied simply by dipping the substrate in the liquid, followed by air drying. Spraying, laminating or spinning of dielectrics can also be used. Lasers that can be used for patterning include those that heat the substrate rather than the coating. This has been successfully tried with wax and photoresist using a CW argon ion laser. A pulsed Nd-YAG laser has also been used, with...