old pcb method, vintage pcb, fr4, bakelite

[macboy]

Originally posted by Christer


I have thought about trying that but has been afraid it won't cope with the ironing since it is plastic. On the other hand, maybe it gets even hotter in the printer? Theay are after all made for laser printers.

I will test it the next time I make a board. It would be a lot simpler if not having to soak the board and remove the paper.

Right. The fuser in the laser printer (or photo copier) is extremely hot - at least as hot as your iron. That's why you need a laser-printer specific transparency. The ordinary kind would melt and make a mess of your printer! Some have a slightly textured surface on one side; this is for the printer's rollers to get some grip while pulling the sheet through the printer. Make sure you print on the smooth side!

Also try printing onto paper and photo-copying using a high-quality machine at a copy shop, if your laser printer doesn't give good results. Different printers and copiers will produce different results. Toner thickness, line sharpness, and even-coverage of large areas all vary widely on different machines. If you have access to different machines at work or at school, try several. If the result after peeling doesn't look good enough, clean the toner off with some kind of solvent and try again. As with the paper method, you will need to experiment with iron temperature, time, and pressure, to get good bonding without bleeding. And different brands of transparency sheets probably bond with the toner differently too.

It helps to carefully examine and touch-up the traces with a sharpie marker after peeling, to fix any cracks, gaps, or thin spots.

[Christer]

Originally posted by anatech

Now I just have to buy an iron. There is no way my wife will let me use hers! Can't say I blame her either.

Why? I use a cotton towel between the board and the transfer film/paper to be ironed, so I won't overheat it (the transfer paper).
That won't hurt the iron. you should use an old cotton towel, though, since it is likely to get a bit brownish.

[Christer]

Originally posted by macboy

Right. The fuser in the laser printer (or photo copier) is extremely hot - at least as hot as your iron. That's why you need a laser-printer specific transparency. The ordinary kind would melt and make a mess of your printer! Some have a slightly textured surface on one side; this is for the printer's rollers to get some grip while pulling the sheet through the printer. Make sure you print on the smooth side!

Yes, I know it gets hot in there, but on the other hand, that's for a very short time, so I guess that is why I didn't dare to try ironing any transparencies. One has to iron them for a while to get a good result, but maybe that goes faster too with transparencies than with photo paper? Oh well, I will try it next time.

[valvusmusicus]

Hi All
Fascinating thread. Im interested in getting the old 70's style darkish brown PCB material to mend some vintage guitar pedals-all the board nowadays is a light tan colour ora light green!
Any sources for this please

[gain-wire]

valvusmusicus, I have seen old fr4 from Rayhteon (supposedly) on ebay. from what seller I don't recall. but I have also wanted to get my hands on older, brown material. there used to be a place herein Ottawa, that sold really old fr4 in bare copper boards. They were made by a company called... oh, I can't remember, it started with an a. I'll ask a friend. But your best bet is ebay or all those wonderful electronics surplus stores there are in the USA. (there ain't none left in Canada, cause there isn't enough population). Maybe in "Torana"...

[gain-wire]

I am glad my thread has generated so many comments, and lasted 6 years!

[AuroraB]

The "old" brown boards were usually a phenolic paper sandwich, not fiberglas FR4

[djQUAN]

there are some "brown" boards that aren't phenolic. I don't think the military uses phenolic in high reliability applications.
Wierd military computer boards

[AuroraB]

Circuit boards are made in a large variety of colours and materials, particularly for pro or high-rel use. Coating laquers and solder masks often camouflage the colour of the base material. Consumer grade boards were still mostly paper-phenolic up until the late 70s or so.

[marce]

Most base material is pretty much the same colour, the type and colour of the final coating determine the finished products colour more than anything else.
The paper-phenolic (CEM) were usualy a lightish cream colour when new, often deepening in colour with age. These were only used for simple designs. Where more layers were required and SMD FR4 based laminates are generaly used (with more exotic materials used for very high GHz applications).Felx and flex rigid boards can have a brown apearance due to the polymer used for the flex laminate. Also in the past a variety of coatings where used to protect circuitry and boards, again having a variety of colours from quite clear to a dirty brown. FR4 (the most widely used laminate base) is just flame retardent GR5 based fibre glass.
CEM and paper based are now only 2% of world production of PCB's now, not often used.