0.4mm PCB prototyping, cheap and reliable place? - Page 1
Forum section: electronics / projects

author: step_s
author_rank: Regular Contributor
timestamp: March 18, 2017, 07:23:44 pm
content: Hi guys.I have some 0.4mm PCB designs that I want to test out, but I need help with the manufacturer.Many places pop up when searching Google, but they are all pretty pricy for a very small prototype board.If anyone knows or uses a reliable place, I would love to hear from youThanks in advance!

author: Benta
author_rank: Super Contributor
timestamp: March 18, 2017, 07:37:39 pm
content: Size?Do you really need 0.4 mm? If you can go to 1.0 mm it's easierHow many?

author: DaJMasta
author_rank: Super Contributor
timestamp: March 18, 2017, 07:45:15 pm
content: If you can afford to use 0.6mm thickness instead, there are several cheap options. I don't have a specific place to look for this, but maybe at that thickness you'd be better off looking for flat flex prototyping options.

author: Howardlong
author_rank: Super Contributor
timestamp: March 18, 2017, 08:19:06 pm
content: You haven't mentioned the reason for using 0.4mm.If it's single or double sided you could consider making it yourself. I often use CIF ABC16 pre sensitised double sided FR4 for RF stuff. Using the thinner board means I can use thinner traces for impedance controlled RF, thus packing higher density.

author: step_s
author_rank: Regular Contributor
timestamp: March 18, 2017, 10:26:30 pm
content: Thanks for your answersThe reason for the 0.4mm is due to it being used with some SOT23-6 chips on top, making it exactly 1.5mm thick, of which there is no room to spare. Also the 0.4mm board fits directy in to a micro USB male connector, whereas 0.6mm seems to be a little too thick, and gets damaged sometimes.The board is very small, around 10x10mm, but there being multiples on one board is no problem.The design is double sided, but the traces are 0.3mm thick, and the cleareance is 0.3mm as well. Isn't this a little too small to do yourself?Have made some 1mm boards myself, but etching seems a little unreliable for these tight tolerances.

author: DaJMasta
author_rank: Super Contributor
timestamp: March 19, 2017, 06:12:42 am
content: The traces are 0.3mm?! That's some serious copper if you didn't just leave off the first zero...What kind of volume are you making these from? if it's just a few, then you may be able to cut a hole under the package and flatten the leads to have some of the thickness of the chip be absorbed by the thickness of the board.This sort of thickness is definitely going to be possible hand assembling, but it may be wise to make a jig of two plates the right thickness apart - any stray spikes in your solder joints could put you over the height limit easily.

author: step_s
author_rank: Regular Contributor
timestamp: March 19, 2017, 12:09:39 pm
content: @DaJMastaThank you for replyingThe data lines are currently 0.3mm, but I could beef them up a little to make it easier to hand-make them.The clearance is still 0.2mm in some places, due to that being the spacing between the pins of the USB connector. I might be able to push them to 0.3mm clearance between the pads, but increasing clearance here, will reduced pad width (since it still needs to fit the micro USB connector), and it seems that it's easier to remove thin strips of copper, rather than preserving thin strips (they often peel off the board), when etching at home?Sinking the IC's in to the board seems like too much work when the 0.4mm boards are already there for the purposeDon't quite understand what you mean with the two plates you mention last. Would you care to explain?

author: DaJMasta
author_rank: Super Contributor
timestamp: March 19, 2017, 02:46:38 pm
content: To be clear, we are talking about board thickness rather than trace width, correct? 0.3mm copper thickness would be something like 20-30oz copper, your typical 1oz copper board should only have traces with a 0.035mm thickness - though you could make the width of the trace whatever you wanted.The two plates thing, though you could actually do it just with a slot now that I'm thinking about it, is just a check for the full thickness of the board. You make a slit that is as wide as your maximum allowable thickness and a length that fits the board. Then you pass the assembled board through the slot, if it catches on anything, then you have some components that are too thick for the final assembled unit.

author: step_s
author_rank: Regular Contributor
timestamp: March 19, 2017, 03:20:41 pm
content: Yes, the 0.3mm is the trace WIDTH, as well as the clearance between traces. The only thickness here is the board at 0.4mm, (due to most manufacturer bumping up the price on these) as well as the total assembly thickness of 1.5mm.Ah, I see the point with the thickness measuring. Making the irregular assembled parts get stuck, and letting the good ones pass.My question now, if I'm going to try making them myself, is whether I can test etch with normal 1mm boards (0.035mm copper) and use the things I learn on the 0.4mm boards when I receive them?Was looking at these, but can't see copper thickness:http://www.ebay.co.uk/itm/142213928272?_trksid=p2060353.m2749.l2649&var=441281512310&ssPageName=STRK%3AMEBIDX%3AIT

author: Howardlong
author_rank: Super Contributor
timestamp: March 19, 2017, 04:02:38 pm
content: 0.3mm track and gap is definitely DIY teritory if you have a reasonable process set up, if not I recommend you practice first.The biggest problem for DIY is vias, or drilling small ones anyway. I use 0.6mm drill for diy vias, any more and drill attricion becomes unmanageable.

author: step_s
author_rank: Regular Contributor
timestamp: March 20, 2017, 04:52:35 pm
content: Howard, how do you do the vias? What do you use a bridging material?

author: CM800
author_rank: Frequent Contributor
timestamp: March 20, 2017, 05:02:45 pm
content: Quote from: step_s on March 20, 2017, 04:52:35 pmpeople usually do copper rivets or just a bit of copper wire, soldering each end.

author: Howardlong
author_rank: Super Contributor
timestamp: March 20, 2017, 06:20:46 pm
content: Quote from: CM800 on March 20, 2017, 05:02:45 pmYes I use copper rivets but no riveted, just soldered on both sides. The riveting machine isn't worth the hassle and the dies break far too easily.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 20, 2017, 06:27:11 pm
content: Eurocircuits do thicknesses down to 0.2mm, but npt a pooled service so will be expensive for small qtys.As soon as you go away form standard thicknesses you lose the big cost savings for pooling, so you can expect tooling and minimum-size costs of several hundred $PCBCart do offer 0.4mm on their prototype service

author: mjs
author_rank: Regular Contributor
timestamp: March 20, 2017, 07:17:29 pm
content: PCBWay has 0.4mm as standard option.

author: step_s
author_rank: Regular Contributor
timestamp: March 21, 2017, 04:24:58 pm
content: I have some small drills at 0.5mm which should be able to make some very small vias. Could use a wire to test it out.A quick question for how vias are made: Do they drill out the outer diameter of the annular ring, plate it, and then drill out the inner holesize afterwards?I know this is more of a manufacturing question, but since I want the soldermask to cover the vias, won't it flow down the hole?@mikeselectricstuffI did check out PCBCart and they seem to be able to make 5 of these boards at around 40dollars, which is by far the cheapest yet. Also their prototype capabilities are quite formidable.Have you used them yourself?

author: Siwastaja
author_rank: Super Contributor
timestamp: March 21, 2017, 05:05:19 pm
content: Quote from: step_s on March 21, 2017, 04:24:58 pmNo. They drill a hole (slightly bigger than the final diameter), and plate the hole walls.You can order soldermask covered vias (called tented vias) - you can order tenting on one side only, or on both sides. Each choice has its own set of advantages and disadvantages. Most often, I order bare vias (no tenting on either side).

author: step_s
author_rank: Regular Contributor
timestamp: March 21, 2017, 07:24:49 pm
content: @SiwastajaThank you for you answerDoes the tented vias require anything special, other than making sure the soldermask Gerber file doesn't have a stop on the vias? Or do they plate the entire hole, to make it fill maybe?

author: Siwastaja
author_rank: Super Contributor
timestamp: March 21, 2017, 07:54:56 pm
content: Depends on the manufacturer, but typically it's defined simply in gerber by controlling whether there is a solder mask opening in the solder mask file, or not."Tenting" means there only is a small layer of soldermask, the via itself is filled with air. Some manufacturers can plug a hole with the soldermask material, or some other dielectric filler material.Holes filled with copper are possible with some manufacturers with extra price. This makes sense for power electronics for thermal transfer as well as high current rating.I like bare, untented vias because they are robust and simple, and they get the HASL surface treatment too, making them even more robust (and increasing the thermal and current capability) for no extra price. I also like that I can use them as test points.

author: dimkasta
author_rank: Regular Contributor
timestamp: March 21, 2017, 10:47:19 pm
content: Elecrow can go down to 0.2mm on their premium pcb service.I have not used the premium, but I have only good things to say about their vanilla prototyping service. And they have excellent response and support times in case something goes wrong.

author: step_s
author_rank: Regular Contributor
timestamp: March 21, 2017, 11:01:55 pm
content: @SiwastajaI see. Then I will just leave the Gerber as is.The bare vias er great for testing, but it wont be relevant here@dimkastaDamn, down to 0.6mm prices are extremely good. . . Guess I'll try and send them a premium request with the 0.4mm boards to hear their price. Thanks for the tip

author: dimkasta
author_rank: Regular Contributor
timestamp: March 25, 2017, 05:34:14 am
content: Did you get a quote?

author: viperidae
author_rank: Frequent Contributor
timestamp: March 25, 2017, 09:11:13 am
content: Could you use a thicker board and route out a hole for the sot23 and mount it upside down?

author: KL27x
author_rank: Super Contributor
timestamp: March 26, 2017, 11:24:39 am
content: ^ creative solution. I like.For some reason, when I ordered 0.6mm boards, my fab recommended silver plating over HASL. Probably something to do with cracking of traces?For thinner boards, I sometimes make them myself IF they don't need a lot of vias or any soldermask/silkscreen. I easily do 8 mil (~0.2mm trace/clearance) on boards all day. On a board this tiny, I imagine I could easily do 6mil traces with high yield, if I didn't mind screening them more carefully.But... humongous vias, yeah.One good thing about boards that are really thin, you can easily see your registration on the vias and fudge them a little when drilling. So if thin enough to be transparent, you can make your vias quite a bit smaller.