WHY dpcb ?

Kirt Blattenberger of www.RFcafe.com asked in a recent email “what is your motivation for diving into this realm?” referring to the realm of Desktop PCB printing.

Kirt has been running RFcafe.com for about 2 decades now, and over that time we have exchanged a few emails. A few days ago he re-posted a 1949 article from Radio & Television News magazine on “Printed Circuits.” The coincidental timing was interesting, so I sent off a quick note to Kirt to let him know what I was up to.

His response email included the question “why?” Before I answer that, let me post a couple of paragraphs from his email to me.

Having read a lot of the vintage magazines I have seen some of the original “printed” type circuit boards. While they quickly went out of vogue once photo etching was invented, I remember back in the 1980s when working with MMIC circuits at Westinghouse that many of our military and space qualified packages used PCBs that were silkscreened and fired with a metal paste for the traces, then silkscreened and fired again for the thick film resistors, and then finally after the resistors were laser trimmed we mounted bare semiconductor die and passives for wire bonding with 1 mil gold wire. So, “real” printed circuits did survive past the 1950s, but they were normally not where most people would see them. 

Sometime around the late 1980s when PCs were becoming more commonplace in the prototyping labs, I got to play around with the circuit board routing machines that used a super high speed carbide bit to rout out copper clad substrates. They worked fairly well, even for controlled impedance lines, but the biggest pain was a lack of solder mask that made soldering fine pitch packages nearly impossible. Solder bridges formed very easily without the mask.

Then this morning, on RFcafe.com, Kirt posted a few sentences and a link to LPKF desktop laser PCB machine. “Fabricate PCBs at Your Desk” article at MicrowaveJournal.com is a brief introduction to the LPKF CircuitPro PL 3.3. LPKF has been making ‘milling machine’ style PCB prototype machines for a very long time, and they do a fine job.

So what was / is my motivation to enter “the realm” of DPCB?

My motiviation is that so much stuff is no longer available through-hole, and it’s getting worse every month.

“Surface mount” technology itself, is not the problem for prototyping, it’s the pin pitch. Most places I have worked produce very small volumes of anything. Sometimes only 6 per year. So it was ‘impossible’ to consider a professional board house for assembly. “No problem,” just stuff and solder them myself as required (“on demand manufacturing” 🙂 That was so easy when nothing had a pin pitch smaller than 2.54 mm (0.1 inch to Americans.)

But these days we are forced to use surface mount, and with hand soldering, TSSOP is my limit. And a TSSOP-14 takes me about 15 minutes EACH to solder, inspect, and use a dental pick to remove solder bridges.

I have been looking for years for anyone that could “stuff and reflow” just a few boards at a time. I got so frustrated, I looked into doing it myself. So I bought a DPCB machine.

With the right DPCB machine, it’s just so easy:

  • load the gerbers
  • click “deposit paste”
  • manually place components
  • click “reflow.”

I chose the machine I now have because it will drill and print. It’s such a pleasure to watch the machine drill nice straight row of holes ! Drill vias also.

Leave a Reply

Your email address will not be published. Required fields are marked *