C5Mick sent me some photos of one of his CB boards asking if in my opinion the board had been overheated. The reason behind his thinking was the insulation appeared to be bubbled, possibly from heat.

I was glad to inform him that this was a production feature. I'm not an expert concerning the production of the C5, but it appears that over the production period certain changes were introduced.

In the photo below you can see there is a difference, with respect to the lands, between the two boards. According to the print on the boards the upper one was produced 2/1/85 and the lower 28/2/85.

The upper board appears to have bubbling in the insulation, but upon close inspection I found the bubbling was in fact solder under the insulation. They seem to have applied the solder like the squeezed out decorative icing on a cake. If you look carefully you will see the solder is in a continuous long zigzag pattern. Why and how they did this leaves me wondering.

So at some point in the game they gave up with this soldering technique and left the solder out completely.

I have checked a couple of my other boards, 13/12/84, 20/12/84, and both are with solder. So it appears that at sometime between early Jan. 85 and end of Feb. 85 the production was changed.