Anyone know how to order pcbs like this?

[kidb]

Hey, I've noticed fr4 type pcbs overtime went from murky light green to now yellow. Anyone know what to specify when ordering pcbs to get the watery green type? Recreating clones of old pcbs, would like it to look similar. Typically one sided boards with no mask. Thanks!

 

[zamproject]

To me it just look like raw glass fibre pcb without (coloured) varnish ?
It's easy to do with restricted mask area (at leas with KiKad that I use).

Now the advantage of proper PCB finish with solder mask is the copper traces being protected from oxidation...

 

[Brian Roth]

Hey, I've noticed fr4 type pcbs overtime went from murky light green to now yellow. Anyone know what to specify when ordering pcbs to get the watery green type? Recreating clones of old pcbs, would like it to look similar. Typically one sided boards with no mask. Thanks!

I don't have a good answer for you. I can only make some comments from when I was "in the trenches" circa 1970's into the 80's.

Back them, FR-4 came in any color you wanted.....as long as it was a shade of green (or so it seemed)! See pic below from a desk module prototype I built.

As you can see, the PCB house I was using (a local company) stocked two different brands of FR-4. AFAIK, that's all they offered. So, the shade of green depended on their stock on any given day. Other PCB companies were the same way.

Solder mask was an expensive option for low-medium sized runs, as were double-sided boards. To protect the exposed copper traces, pro PCB companies either solder plated the traces or used an electroless tin plating option.

In 2025, I guess you'll have to inquire at each potential supplier (maybe ask for a sample) and see if you find something close. Wish I had more suggestions.....

Bri