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

 

[jp8]

The soldermask-free areas on my PCBs from PCBWay and JLCPCB look greenish. So I'd just order from there.

These soldermask-free areas are within guardring loops. But I keep the rest of the board covered with soldermask for the reasons already mentioned by other members and to prevent solder bridging. Enjoy the progress of technology!

Jan

 

[Matador]

Just ask the board house to skip the soldermask layers, and you'll get the blank un-colored FR4 material with exposed bare copper.

You also need to ask the board house if they can support HASL or ENIG (or even Sn immersion) if there is no soldermask - I seem to recall, that HASL was possible without soldermask, but not ENIG (but ask them to confirm).

 

[Matador]

I forgot to say: skipping the soldermask is a Horrible Idea (TM). Not only does soldermask prevent oxidation of the traces:

1) It greatly reduces moisture penetration/contamination
2) Reduces the chances of shorting traces with tools/test clips/probes/etc.
3) Stops solder from wicking up the trace, thereby draining it from the connection(s) you are trying to make
4) Silkscreens have more contrast, and sharper printing of edges (e.g. look better)
5) Makes it harder to bridge between adjacent pads
6) Easier to clean flux residue with stronger solvents without damaging anything on the board