Homebrew PCBs

A cautionary tale.

So I have been selling sheets (12x17cm) cut off my roll of dry film 
[which I bought from China], not making money really, more as a service 
to my fellow New Zealanders who might want to give it a go.

Anyway, I had been trying to think of a way to post it for as cheap, and 
little packaging effort as possible.

I started out sending it flat in a sealed cardboard envelope, one stamp, 
this worked fine, but actually getting it flat and into the envelope was 
always an exercise in frustration, and took me about 10 times longer 
than it should have.

So then I started to send it in it's natural "curl/roll", but I had to 
use (make) a package out of sturdy cardboard to ensure it wouldn't get 
crushed (and therefore creased), this wasn't really a problem, but it 
did push the post up from just 70c for the flat envelope, to now $2.70.

So, long story shorter, I was in one of the local "cheap stuff from 
china" type shops and I happened across some long lollipop sticks, and 
some tissue wrapping paper.  Aha!  I thought, perfect!  I cut a piece of 
tissue paper larger than the film, then roll the film and paper around 
the lollipop stick, like a sponge roll, a bit of tape around the outside 
with a tab to pull it open and they could be sent for just 2 stamps.  I 
made up a test roll as to how I would send it, and then unrolled it to 
test that it would be easy to "unpack", and I looked at the film, and it 
looked just fine.

So I made up some of these rolls, and put them in my box which I keep in 
the dark recesses of my office cupboard with the film roll.

Come a week later, and somebody wants to buy some.  So I grab out the 
rolls.  I had to make up one more, which I did, then packaged 
everything.  But before I sent it, something in the back of my mind said 
"James, you know, maybe you should do a quality check on one of those 
rolls you made up last week.. just in case".

So I de-packaged the order and took a look at a random roll.  And it's 
just as well I did.  The photo sensitive layer seemed to have, for want 
of a better word, wrinkled, or crinkled, or rippled, even though the 
protective layers were fine.  I tested some to be sure, but it's not 
usable (adheres to the board normally, but the developed image is like 
crinkle-cut chips).

My roll of dry film, and a few loose cut sections I have, which were all 
stored in the same place, were fine.  The one I had made up earlier 
today, it was fine, so I think it must be something to do with being 
rolled up tightly (5mm core diameter) for a period of time.  It's fairly 
warm in my office, so perhaps that has something to do with it, but all 
the other film is fine, just these rolled up ones bit the dust.

Luckily I had only made up 10 rolls like this, I've now undone them all 
and put them flat between some card and a heavy thing in a warm place to 
see if there's any hope of resurrection for my personal usage, but I 
doubt it somehow.