How To Get 5 Different "Colours" On A PCB - Page 1
Forum section: electronics / general

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: April 30, 2022, 09:04:20 am
content: Hi Dave,glad to see the package made it. I already feared it had gotten lost on the way to down under as it has been several months since shipping. Quite the queue for the mailbag I guess.Anyway, here's some background on it:Bobs face was taken from an old Linear Technology Ad found here:http://analogfootsteps.blogspot.com/2014/02/guru-1-bob-widlar.htmlTo vectorize the image and reduce it to 4 colours, I used Inkscape which took a lot of experimenting wih the import filters.The result still had to be edited manually to remove details that were simply to small to be manufactured.Kicad 6 has recently gained a convenient way to import graphics, however, this PCB was still done in KiCad 5.I used a script called svg2shenzen found here:https://github.com/badgeek/svg2shenzhenHad I known that Kicad 6 was getting that feature just weeks later, I'd have waited and saved myself a lot of troubleI was thinking about adding more of Bob's brilliant parts, however, I changed my mind after having had much more trouble getting just the three parts than expected.Of course the absolute nerd thing to do would be hunting down parts from the very first production week. That is probably impossible without getting the help from old LT staff.It looks very nice with the parts fitted on the wall of my lab:Once the mailbag episode becomes available I'll open a thread with the project files and the gerbers.Cheers

author: okurka
author_rank: Contributor
timestamp: April 30, 2022, 10:24:30 am
content: Spending all that time and then spell "volage regulator".

author: RoGeorge
author_rank: Super Contributor
timestamp: April 30, 2022, 10:30:01 am
content: Quote from: okurka on April 30, 2022, 10:24:30 amMight be 8 types of layers:1. silkscreen2. solder mask3. fiberglass translucent4. fiberglass with copper on the other side5. bare copper6. solder7. gold8. holes/panel cuts

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: April 30, 2022, 11:13:58 am
content: Quote from: okurka on April 30, 2022, 10:24:30 amNot my finest hour, indeed.Another bug is that I had it made at JLCPCB and forgot to put the JLCJLCJLCJLC mark on the backside. (Wanted to use a different boardhouse at first.) So they went ahead and plastered it right in the middle. DOH! All Fixed in Rev B.

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: April 30, 2022, 11:40:47 am
content: Quote from: RoGeorge on April 30, 2022, 10:30:01 amYou can't get copper without surface finish. The bar metal surfaces will either be all ENIG or HASL. While theoretically possible, probably no PCB manufacturer would do this for you. It would require them to do an additional photoresist step on the finished board. I also expect that regular photoresist paint would not be able to resist the tin bath preceding a HASL finish.

author: EEVblog
author_rank: Unknown
timestamp: April 30, 2022, 11:46:48 am
content: Quote from: BreakingOhmsLaw on April 30, 2022, 11:40:47 amYou can aks for it. Most boards use SMOBC, Solder Mask Over Bare Copper. So you can just tell them to skip the plating step. Not on a shared panel though. Selective peelable masking is also possible.

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: April 30, 2022, 12:03:38 pm
content: Oh yeah, completely forgot about peelable mask. Only seen it used once in my career for a PCB that needed a copper strip spot welded directly to it. If I remember correctly we wanted to prevent a parasitic thermocouple.

author: nctnico
author_rank: Super Contributor
timestamp: April 30, 2022, 01:37:48 pm
content: Quote from: RoGeorge on April 30, 2022, 10:30:01 amYou forget inner layers!

author: RoGeorge
author_rank: Super Contributor
timestamp: April 30, 2022, 02:51:26 pm
content: True that, then dithering, too!