Where to get small quartz substrate PCBs made cheaply? - Page 1
Forum section: electronics / rf-microwave

author: mr ed
author_rank: Regular Contributor
timestamp: February 23, 2025, 12:02:23 am
content: I would like to build some really small rf filters, like for 100GHz stuff small, say 10mm x 2mm with copper traces down to 50um, one side cu, in quartz, dk 2 or 3. Where to get cheap?Or how to make it myself? Old school black and white negatives would easily have the sharpness needed, it's the copper deposition and photoresist that seems difficult to acquire on the cheap. Rogers products may work but regular pcb fabs don't seem to have the resolution needed.Any ideas are appreciated.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: February 23, 2025, 02:29:17 am
content: You could try using sputtering to coat everything with a thin layer of copper like in this video:

author: daisizhou
author_rank: Super Contributor
timestamp: February 23, 2025, 02:58:25 am
content: Quote from: mr ed on February 23, 2025, 12:02:23 amWhy not choose Rogers, high-frequency PCB made of PTFE?Soft FPC seems to be possible.There is no charge for individual users, you only pay for the shipping cost

author: mr ed
author_rank: Regular Contributor
timestamp: February 23, 2025, 01:07:28 pm
content: I use Rogers 5880 now. Its great for shf. The video is a project in itself. The chip fab photo resist ($$$) idea may be feasible on the Rogers boards. One important thing many don't realize about this particular Rogers family is that it has the strength and thickness of cereal box cardboard. Cutting and working a real thin piece will be difficult. I will try cutting some today as sputtering won't be possible for me, turbo molecular pump and all that entails.

author: daisizhou
author_rank: Super Contributor
timestamp: February 23, 2025, 01:27:44 pm
content: Quote from: mr ed on February 23, 2025, 01:07:28 pmIt costs almost nothing to make these PCBs in ChinaNormal charges will only apply if the area is larger than 10cm x 10cm

author: mr ed
author_rank: Regular Contributor
timestamp: February 23, 2025, 02:02:46 pm
content: I need better resolution. Most pcb standards are a bit under 0.1mm which is too big/rough a tolerance.

author: twospoons
author_rank: Frequent Contributor
timestamp: February 24, 2025, 12:38:34 am
content: I'd start with electroless silver for the conductive layer - the old fashioned mirror making chemistry (ammonia, silver nitrate and dextrose). Then either stay with silver, or plate up with copper, but since silver is the better conductor ...Not sure what you'd do for lithography and etch though.

author: coppercone2
author_rank: Super Contributor
timestamp: February 27, 2025, 03:16:43 am
content: Electroless copper does work on ceramic, I had almost great results but all the stumbling around to that point make me take a long breakIf you combine this with a high resolution dry film maybe you can get to 0.0019685 inches resolution.Building it up to thin levels is pretty easy, but even if you start messing with additives, it starts getting lumpy when you go thicker.I don't know if it would work on quartz though. But I did metalize a polyethylene? translucent washer with copper, and that shit is pretty bad as a material, so it might work on quartzits been 4 months and my palladium still is black color and the tin is still clear, but the copper strike has some copper flakes in the bottle

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: February 28, 2025, 07:10:57 am
content: How about using photoresist, and then doing the silver reaction (assuming none of the chemicals in the silver reaction react with the photoresist)You can then dissolve the photoresist and it should "lift-off" the extra metal.

author: coppercone2
author_rank: Super Contributor
timestamp: February 28, 2025, 07:43:00 am
content: From experience the silver sugar one is weak as hell and also very thin, it came off the glass easily, so you would need to build it up with plating, assuming your adhesion is ok

author: LaserSteve
author_rank: Super Contributor
timestamp: February 28, 2025, 02:03:15 pm
content: Thermal evaporation or Sputtering. Have a layer of nickel put down, then flashed with copper, then you copper plate it. A flash of nickel promotes adhesion.There are liquid solutions made by Hanovia and others that can be "burned off" in an oven and then plated, that was one way done in the past. My experience with the art versions is the trace of bismuth in the Gold artistic version becomes a problem in soldering, and the copper was very dull till burnished. I did not try the silver. The industrial pastes, if still made, do not suffer these issues.Your looking for "low temperature co-fired ceramics" pastes. The materials are available, but will not be available to a hobbyist due to export restrictions. At the time I was working for a university, and to have them I would have had to signed a statement saying I would keep them in a safe or vault, and not distribute to non-US citizens from the East. A citizen of a Five-Eyes country might not face these restrictions.Non US Citizens could use the product once baked but could not handle the raw materials. High resolution is obtainable, and we'll leave it at that.Otherwise have a mirror aluminizing shop for telescope mirrors coat your prototype, or a standard optics shop. Thermal doesn't need a turbo under certain situations, and sputtering is done in Argon at minimum vacuum, often from just a roughing pump.At a former job, I DC sputtered Cu, Pd, PT, and Ni at 20-300 microns Argon , and 20 mA, 3KV DC. The HV transfomer weights about a pound, and fed into a Doubler or Tripler depending on the machine. The electrode is no-where near as complex as the hobby mag sputter systems seen on Youtube. For the noble metals, some times we just used air.Two stage pump, Leak valve, Simple HV supply, Argon, and a Variac for control. Ma meter. Half the time the Thermocouple gauge was dead, and I went by the sound of the pump. 1940s Technology and it worked well.Thermal Evap needs lots of amps, but the cathodes are readily available for cheap if you know where to look.Any electron microscopy lab can show you how.... But they are not used to producing thick layers...Many optics companies have coating facilities for metallic mirrors, so you need copper on quartz, which is a common IR and Far IR optic. You'll just need to say no dielectric "Overcoat" and then plate on more copper.For various reasons I know this is available or was easily available in Ontario. Not sure if those businesses are still there. Heck, even plastics aluminizing shops ran chromium once in a while, which is the other type of adhesion layer. Walk into a plastics aluminizing place and you will be amazed, the aluminum vapor "Is" the final pumping stage.Steve

author: coppercone2
author_rank: Super Contributor
timestamp: March 01, 2025, 04:03:38 am
content: I think its a little crazy that they complain that all the semiconductors are made overseas but they don't want to make it accessible for people to develop traces at home (I would imagine quite a few people would end up going into the industry after learning the basics in their garage / gaining appreciation for it)And its basically seems to be the right flux mixture that is suuch a pain in the ass to get. From what I gathered trying to get into this, its kind of like rosin flux not being available (the 'solder' part is easy enough)maybe you won't get too far but it seems more then a little elitist . Kind of like a really boring version of 'october sky' without rocketsSame thing with titanium flux for brazing. Utter pain in the ass to get it. Why are flux dealers so god damn paranoid???I started to wonder if it has something to do with the dealers being around intense heat. I always felt a little jittery after using the kiln or brazing larger stuff (lots of heat). Something about looking into a kiln makes me not wanna tell people my cookie recipeBut I think these are the fires of creation not the fires of damnation and chill out. The universe is full of extremely hot stuff and its very useful and the reason why we exist. Does the red glow have demonic associations that makes bit into a holy secretAnd it might sound crazy, but this goes back a long way. I read that in ancient china there was a closed city (like a atomgrad) related to pottery making, there was like threat of death related to the secrecy of that whole enterprise lol. You got to wonder the total number of hygiene problems that would be avoided (massive disease outbreaks) if quality porcelain proliferated in ancient times...

author: LaserSteve
author_rank: Super Contributor
timestamp: March 02, 2025, 07:51:35 pm
content: ITAR is why you can't have it.Not going to argue.Steve

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 07:56:02 pm
content: A stunningly helpful law. I wonder how many Americans are still getting sand out of their shoes after having to deal with those super world endangering ITAR violations that occurred in the middle east, starting with fortune tellers discovering the existence of some kind of secret train laboratories and metal pipespentagon intelligenceSometimes I wonder what history will remember in 5000 years about America. I think it will be a pentagon intelligence meme. Egyptians believed the gods were riding around in the sky, greeks believed Thor was smiting people, Americans believed that the pentagon can actually gather and analyze intelligence. Biggest blunders of civilization list.

author: LaserSteve
author_rank: Super Contributor
timestamp: March 03, 2025, 04:10:24 pm
content: When you are older, you will learn why we have that Treaty and the Wassenaar Arrangement.Steve

author: coppercone2
author_rank: Super Contributor
timestamp: March 03, 2025, 05:50:56 pm
content: it will be like the start of the renaissance when lead free 'ceramic flux/binder' proliferates, currently we are in dark ages for this techI would need to join or start a fiefdom and get support of the nobility

author: drspastic
author_rank: Contributor
timestamp: March 06, 2025, 01:53:22 pm
content: i managed to get a thin film of copper onto a glass slide with a homebrew magnetron from a jamjar and microwave oven parts. no turbomolecular pump or diffusion pump, just a mid quality lab pump. no doubt the coating had contaminants but it was conductive although semi transparant. it might be good enough for a substrate and use a cheap laser engraver to blast away what you dont need. its only an atom or so thick

author: mr ed
author_rank: Regular Contributor
timestamp: April 14, 2025, 11:43:06 pm
content: Update: I have managed to get around 50um resolution first try onto a Rogers 5880 board using an old school film camera and the dry film as a mask. I could get a bit better res by perfecting the dry film exposure so little to no undercut happens.I used slow silver based film, high contrast B and W; Rollei 80s. I wish the negative was conductive but it seems not.I shoot from A4 masters down to 35mm.I got one quote for an actual proper quartz based circuit. It's in the thousands usd for 5 or 50 pieces. Not going to happen.