PCB manufacturer and via current comparison - Page 1
Forum section: electronics / projects

author: Philfreeze
author_rank: Regular Contributor
timestamp: July 14, 2016, 10:02:09 pm
content: I just watched EEVBlog #543 because I am trying to go systematically through every video Dave made.In this video he takes a look at the resistance of a via and how much current you should let flow through it.Because I find this very interesting and I actually have never really thought about it a lot until now (never had to design a PCB with >0.8A) but now I really want to get some good data about that.I already designed a small test board with different via sizes and I wanted to order it from multiple manufacturer to see if there are big differences between them. Since I am gonna order from multiple manufacturer anyway I thought this might be a good chance to also compare the capabilities of them and see how good they are.Now I need your help.You have to name your go-to manufacturers so I know which ones it makes sense to order fromAlso, I would appreciate ideas for comparisons.Comparisons I am definitely going to make:Silkscreen (compare accuracy of straight lines, method and minimal line width for good results)Drill accuracy (make about 20 small vias and compare how good the drill was centered)I already talked about the project with my ex boss (I am now again a student) and I can use all the gear they have on the weekend which is nice.He might even give me a small fund for this project but I first have to give him the details.TL;DR:name your favourite PCB manufacturerwhat could one compare between different pcbs (drill and silkscreen accuracy etc.)

author: RogerRowland
author_rank: Regular Contributor
timestamp: July 15, 2016, 04:45:52 am
content: Not sure how much you'll get out of this but personally I tend to use ITEAD:https://www.itead.cc/open-pcb/pcb-prototyping.htmlI've also used SEEED, but the similarity of the result and the price makes me suspect that both ITEAD and SEED use the same fab house.

author: vzoole
author_rank: Regular Contributor
timestamp: July 15, 2016, 06:47:17 am
content: The current handle of via is depending for plating thickness and manufacturers have a big tolerance for this.So comparing manufacturers is pointless because there could be a big difference in same factory too.

author: Donziboy2
author_rank: Contributor
timestamp: July 15, 2016, 10:19:06 am
content: I have used Elecrow and Oshpark in the past.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 15, 2016, 10:40:55 am
content: I think you should order from each manufacturer at least five to ten times during at least half a year or so, so you need some budget and some time, but otherwise, the comparison is totally worthless IMO. This is because the quality difference is in tolerances, and if you order only once, you may get much better then expected results by luck; you can then evaluate between the fabs only if there is an order-of-magnitude difference (or if some fab fails providing within their own specs).Especially the silkscreen process may change suddenly.I always order from the cheapest one fulfilling my spec on pcbshopper.com, and it has always been either Shenzen2u or Pcbway. I don't like their marketing tactics, but the quality has always been fine and there has been no bullshitting even though my orders have had some "special" things going on which are known to cause panic, failing communication and mysterious extra fees with many well-known "hobbyist friendly" fabs.

author: Philfreeze
author_rank: Regular Contributor
timestamp: July 15, 2016, 09:24:31 pm
content: Quote from: Siwastaja on July 15, 2016, 10:40:55 amQuote from: vzoole on July 15, 2016, 06:47:17 amThat was the plan from the beginning, I am gonna order 5 pcbs 3-5 times during a one year period (the exact amount is gonna depend on the amount of fabs).Of course I won't have a complete data set anyway and usually they even have other processes for bigger series production (more than 1000 pcbs or even more). Obviously I can't order that much to test that.The goal is not to get the best possible data and get a definite answer. The goal is more to narrow the range down. That is also why I want to order from different manufacturers because I want the biggest spread possible on my data with a certain budget. This way I should be able to see if the numbers are way different for each fab or if they are all pretty close together and in which range they are.I am probably even going to order two different pcb thickness just to get more data.Quote from: vzoole on July 15, 2016, 06:47:17 amYou say this but do you know how big the differences can be? Because I don't really now it and that is part of what I am trying to narrow down.Quote from: Siwastaja on July 15, 2016, 10:40:55 amYes, the process will obviously change on a regular basis as they will have to buy new machines after a certain number of manufactured pcbs. I won't be able to provide data which will always be relevant but it will provide a nice snapshot.And what I probably should mention is that I am not exactly doing this to provide extremely scientific and relevant data. It is not my job to do so. It is just a hobby and I think it will be fun and I might learn some new things.

author: uncle_bob
author_rank: Unknown
timestamp: July 15, 2016, 11:42:48 pm
content: HiOddly enough I'm in the middle of one of these issues with a defense contractor on one end of the table and a fast turn pcb house on the other end. The pcb house is one we have used for 20 years for quick turn stuff. We never (until now) had to dig dug very deep into their processes. The defense contractor has their own in-house lab complete with scanning electron microscopes (yes plural). We look at cross sections optically and make a call. They haul out the 10,000X gear and see what it really looks like. The pcb house has a few gaps in their system (as do most quick turn outfits). The daily calls are ... interesting.Needless to say, no matter how deep you want to dig into this ... there is somebody else who is quite capable of digging a whole lot deeper.Bob

author: Pjotr
author_rank: Frequent Contributor
timestamp: July 16, 2016, 08:23:07 am
content: Well, the video is a nice illustration that solder conducts electricity better than air. Usually with VIA's that have to carry a substantial current, you simply use lots of them. Most PCB fabs are quite happy to have their plate through process well under control. Indeed Bob, there are a lot more things to take in into consideration. To keep it simple, a few years ago we have had a batch of (multilayer) PCB where the layers came apart during reflowing: It was traced down to the pressing pressure during the baking process. Or what about slight shifts of inner layers... etc. etc.

author: uncle_bob
author_rank: Unknown
timestamp: July 16, 2016, 05:15:40 pm
content: Quote from: Pjotr on July 16, 2016, 08:23:07 amHiWe have had our share of delimitation issues as well. In this case we are after exactly what the topic is about - how much copper is on each wall of every via on every board .... with 100% certainty. Nobody seems to want to send them all out for full 3D x-rays. Actually not quite accurate, nobody has said they will *pay* for the x-ray process and wait the few weeks /months while it's all done and analyzed.Bob

author: vzoole
author_rank: Regular Contributor
timestamp: July 16, 2016, 07:13:22 pm
content: Quote from: Philfreeze on July 15, 2016, 09:24:31 pmAt Eurocircuits the plating thickness is 20-50µm.But you always have to design current handling for the minimum thickness because it is the garanteed and depends on so many things.-hole size and layout of your design-where is your board on a big manufacturing panel-how fresh are the chemicals in plating bath-condition (size) of the copper anode-types (holes and layout) of other boards what are in the same bath (many board is plated same time together)E.g. this two boards was produced in same order and it have 20µm difference at top and 11µm differende at bottom in plating thickness.But it is normal and there is always some difference in production. And it is good until it is between the tolerances.