Homebrew PCBs

How do you tin your boards?  Looking good.  

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] 
Sent: Sunday, January 10, 2016 2:42 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Heatless (cold) Toner Transfer for PCB making

 

  

I have been using toner transfer for years with my Brother printer and a Scotch Tl902 laminator, with great success.  Only problem has been that I need to use a genuine Brother toner cartridge, and have had problems with a little over etching of larger copper pour areas.  Saw this instructable, and thought I would give it a try, since my toner cartridge was almost out and the would have to order a new one soon.  I have a couple generic cartridges that I use for general printing, but they have not worked well for making boards, so I thought I would give them a try.
Looking around at my painting stuff I had some denatured alcohol and a couple of different types of solvent. but no acetone.   I tried a couple to see which one would dissolve toner, and found the Xylene that I used for thinning out some enamel worked well.  I tried different mixtures  and found 4 to 1 mixture of denatured alcohol to  Xylene worked well.   Printed a couple copies of a board layout on Hammermill color laser copy paper, and used a modified version of the method in the instructable.   Using a eye dropper I placed a small amount of the mixture on cleaned boards and spread it around until I had a even coating on the board.  I placed the laser print on  the board and lightly pressed it down so it made even contact with the board.  Then with the eye-dropper I flooded the back of the paper until it became nearly transparent and I could see the pattern through the paper.  Waited about 30 seconds and covered the paper with a folded over paper towel, placed a small piece of board material on top and applied pressure for about two minutes.  After that I removed the board and used the rounded back of a fork and burnished the board, first with the paper towel , and then without.  After soaking the board in water and removing the paper, everything looked nice and crisp.  Good adhesion over the entire board, and no voids that I could see.   I etched the boards, and everything came out great.  Nice clean lines, no breaks in any of the traces, good sharp clearance where I had traces going between pins, and very little problem with etch through on the large ground plane areas.
Looks like time to retire the old laminator.  I will post some pictures of a completed board on my blog.
DuWayne
KV4QB.blogspot.com