Some notes on using Bungard laminates
12.12.2006 23:43
I'll be using laminates made by Bungard for Galaksija's printed circuit boards (they were the only ones I could get that were big enough for the motherboard). I usually buy plain laminates and coat them myself with Positiv 20, but these laminates come pre-coated with Bungard's own photoresist.
I was pleasantly surprised at the quality of the coating (when I bought these plates I thought I would remove the factory coating and apply my own). It is much more even and has less flaws (dust particles, etc.) than what I could ever do with Positiv 20 on such a large surface. I also found out that the photoresist's properties are a bit different than what I'm used to. Here are some notes that might be useful for anyone else using this material:
Exposure
4 minutes under a 500W halogen reflector 30cm away. Exposed parts of the photoresist turn green just like with Positiv 20.
Development
The usual concentration (4g NaOH per 500ml water) seems to be to low. I used 10g per 500ml and it took something like 10 minutes to fully develop. Bungard also offers a special developer that isn't based on sodium hydroxide.
Etching
Photoresist seemed to hold fine in the HCl / H2O2 solution I use.
