how to reduce/eliminate pinholes with TT
2006-12-03 by Stefan Trethan
Hi, I was recently having some trouble with pinholes/etching through of very wide traces or ground planes. Today i realized something very significant: Paper surface influences pinholes, possibly more than anything. I usually use zweckform/avery paper, which has a matte clay finish. I had the holes/etching through with this. But because it was closer i used Verbatim paper today, with a shiny surface. This paper is a little harder to remove, and heavier. After printing i held it against the light and it was _very_ translucent. Because it is heavier than my regular avery paper it will get less toner. I was sure this would leave heaps of pinholes and stuff, since i had to make a PCB with ground planes. To my surprise there is not a single pinhole, the copper surface was pristine under the toner throughout. Even though the toner was obviously more translucent on paper the glossy, flat surface must help in keeping an even toner distribution, or something, that prevents pinholes. The pinholes bugged me, and i'm glad i finally realized why it is that i sometimes got them and sometimes not. I was just thinking my toner must run out, but this paper works perfectly. Anyway, may seem obvious, but it took me long enough to realize it so if you get pinholes try a glossy paper instead of a matte clay paper. This paper is a bit harder to remove, and tends to peel off the board outline or outermost traces. But that can be controlled by drawing a fat board outline around the actual PCB. ST