The Innerlayer Line

What is going on in this step

RD Chemical offers this technology

1. Prepare (Clean) Copper for photoresist

Typically a 2 step chemical clean, alkaline cleaner followed by microetch. Use of a microetch in this step is not the ideal, if the alkaline clean first step is done right, a mild acid cleaner is all that is required.

RD Chemical “No-Microetch” concept, gives very high, consistent yields, at low cost per square foot processed, with easy waste treatment. Specific recommendations must consider quality of incoming Copper, and substrate type.

2. Apply Photoresist

Liquid or Dryfilm,

3. Image

Image pattern of circuitry desired

4. Develop

Create pattern on PCB by washing with Sodium or Potassium Carbonate solution. It is critical for modern fine-line patterns that developer be clean, and have uniform spray pattern.

RD Chemical offers an excellent developer, but particularly important, offers both high quality defoamer, which does not generate scum, and outstanding developer cleaner, to return developer (and stripper) to “as-new” condition

5. Etch Copper, create circuit pattern

Done with either Cupric Chloride, or Ammoniacal etchant.

RD Chemical offers Cupric Chloride etch replenisher

6. Strip photoresist

Usually done in conveyor spray, often in one continuous Develop, Etch, Strip line (DES)

Photoresist is easily stripped at this stage of fabrication, important factors are particle size of stripped photoresist, and tarnish, which can lead to “false defects”, and slow the AOI process.

7. Automated Optical Inspection (AOI)

Panel inspected by laser, to ensure properly done. This process seriously slowed by tarnish, which is seen as a “defect”. This happens because of tarnish caused by previous step.

RD Chemical has most effective anti-tarnish system built-in to its photoresist strippers, and stripper additives.

8. Oxide

Usually a two step process, cleaner followed by oxide application.

RD has developed (& patented) best, lowest cost, most easily controlled oxide system, (ChemBond EC2) but it is still being finalized at beta site.

9. Laminate innerlayers

This makes a tight sandwich of innerlayers,

After this step, the panel is treated as an “outerlayer”