I have had great success in the past using the reflow soldering method, using a syringe and needle to apply the paste to the board. However, I found myself repeatedly making the same boards so I decided to purchase some stencils.
I purchased a framed metal stencil for one PCB design and a 4 mil mylar stencil for the other.
They have worked well, until one day I forgot to clean the stencil after use. Now the solder has hardened and it is not wiping off.
Is there something I can use to dissolve the solder so that I can wipe it clean? Also, do I use different products for my metal stencil and mylar stencil?
NB. I am using no clean solder paste by AIM: http://www.aimsolder.com/products/No%20Clean
Best Answer
I have found that the best solution (pardon the pun) is to use Isopropyl Alcohol (IPA). It removes the solder with the least amount of effort. I have had no problems when I have used Isopropyl Alcohol with the no-clean varieties of solder paste.
Methylated Spirits works as well but not as well as Isopropyl Alcohol.
Isopropyl Alcohol will be fine on mylar stencils.
I have found that it is best to use an old rag when cleaning off the solder paste. Tissues etc. catch on the holes and rip, leaving bits of tissue behind in the holes. Steel/wire wool also catches in the holes and pulls and can damage the stencil.