Wet promotion
A-174 silane is available for adhesion promotion if improved parylene adhesion is desired. Wet promotion is a treatment process that is performed on the substrate before it is loaded in the coating machine.
Making the promotion solution
The promotion solution is made of 99% pure isopropyl alcohol (IPA), deionized water (DI), and A-174 silane solution.
Mix equal parts of IPA and DI, then add 0.5% (1 part to 200, by volume) of A-174. The shelf life of the solution is 24 hours, so mix only the amount that will be used during that time.
A-174 silane is a skin sensitizer—wear nitrile gloves when handling to avoid skin contact and be cautious when dispensing from the A-174 silane container spigot. See SDS for more details.
- Stir the solution with a clean stirring rod for 30 seconds and allow the solution to stand for at least 2 hours (to allow adequate chemical reaction) before using it.
Quality check, disposal
- Use a pipette or dropper to place 6–10 mL of the promotion solution into a clean, dry 100 mL beaker.
- Carefully add 3–4 grains of potassium permanganate to 100 mL beaker.
- Agitate the sample by gently swirling the beaker contents until grains have completely dissolved. DO NOT mix the sample in any other way.
- Observe the colour of the sample: A good solution will turn yellow-brown (much like apple cider). This indicates that the solution is ready for use. A bad solution will turn bright pink—this colour indicates that a fresh batch of promotion solution is required.
- Dispose of the old/bad test solution in the solvent waste bottles in Wet Decks 1A/1B/2A. Rinse the test items and all containers thoroughly in IPA before conducting another test.
How to use promotion solution
- Submerge the parts in the prepared promotion solution for 15–30 minutes.
- Remove the parts from the solution and allow them to air dry for 15–30 minutes.
- Submerge the parts in IPA for 15–30 seconds. Agitate the basket of parts up and down several times.
- Remove parts and drain adequately (approximately 30–60 seconds).
- Dry parts with a N2 gun.
- Dispose of the used adhesion promotion solution in the solvent waste bottles in Wet Decks 1A/1B/2A.
- Parts should be coated within 30 hours, maximum. If parts are not coated within this time, parts must be re-promoted, repeating this process.