Board Houses Changing Gerbers - Page 1
Forum section: electronics / general

author: b2theory
author_rank: Contributor
timestamp: April 16, 2021, 12:40:13 pm
content: Does anyone else have trouble with board houses changing the gerbers during penalization? We haven't seen major issues but they will do quasi cosmetic things with vias (tear dropping all the vias, enlarging them... etc).

author: krish2487
author_rank: Frequent Contributor
timestamp: April 16, 2021, 03:55:45 pm
content: Quote from: b2theory on April 16, 2021, 12:40:13 pmI dont know about you... but if a board penalized my gerbers.. I wouldnt use them ever again!!!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 16, 2021, 04:48:47 pm
content: What do you mean "trouble"? It's standard industry practice, every manufacturer tweaks the data to their process. It's normal. You can ask to review the data before manufacturing.Typically only for RF boards like C-band and up would I put in a note for "do not modify" or have a discussion with the shop before building.

author: b2theory
author_rank: Contributor
timestamp: April 16, 2021, 06:04:43 pm
content: Quote from: Alex Eisenhut on April 16, 2021, 04:48:47 pmI always ask to review my boards before production, but I was just reflecting on it a bity today. In the aerospace world that would be unacceptable.

author: MarginallyStable
author_rank: Regular Contributor
timestamp: April 16, 2021, 07:24:36 pm
content: The aerospace industry doesn't usually go to the cheapo shared panel services either. Also the boards will be specified to be Class 2 or 3 depending on criticality, which brings all kinds specified requirements on both the PCB itself and the process' that produce it. I have never had a board house modify a class 2 or 3 specified board without first requesting engineering approval.

author: thm_w
author_rank: Super Contributor
timestamp: April 16, 2021, 08:21:35 pm
content: You need to be more specific, which company and what did you pay?If its JLCPCB or any other low cost vendor, as mentioned, nothing to do about it.No this is not "industry practice" for any high quality NA PCB vendor. They will call you before making any modifications, or if they see anything unusual.

author: tszaboo
author_rank: Super Contributor
timestamp: April 16, 2021, 10:51:35 pm
content: Quote from: thm_w on April 16, 2021, 08:21:35 pmOh, they touch up on your gerbers, for sure.Standard is removal of silkscreen from bare copper. Solder mask slivers are removed. If you order PCB from the assembly house, they might change the solder mask expansion on pads. They will routinely change paste masks.Recently I received boards, where they removed tenting from all vias, when I carefully placed them in strategic locations, to pass a certification. That's when I lifted the phone and started shouting with them about who the hell they think they are. We scrapped the entire production batch.My other favorite was, when our purchasing guy asked the PCB assembly house to replace the board designator name on the gerbers, with something else. Because they had a different name for it in the ERP system. And I have a schedule drawing stamped by a notified body, that these are the gerbers, and we cannot change it.Its a good thing that he already was leaving the company, saved me the trouble of getting him fired.

author: james_s
author_rank: Super Contributor
timestamp: April 16, 2021, 11:20:36 pm
content: Totally normal for the low cost hobbyist oriented board houses. They panelize your boards with boards from multiple other customers and fabricate them all together so it's only natural that they'll sometimes make a few tweaks to reduce the number of different tools used or other minor changes to ease manufacturing. It has never been a problem for my boards but if it isn't going to work for you then you'll have to pay more to have your boards made to a higher standard. You get what you pay for to some extent, I remember paying $200 to have 10 PCBs made back around 2005 and that was a breakthrough in low cost and small volume for high quality boards. Today that same set of boards would cost me around $20. 10 years earlier it would have probably cost thousands.

author: thm_w
author_rank: Super Contributor
timestamp: April 16, 2021, 11:23:21 pm
content: Quote from: tszaboo on April 16, 2021, 10:51:35 pmSilkscreen, yes valid point. That should never affect your design though.Soldermask, hopefully they refunded or remade the boards.

author: KL27x
author_rank: Super Contributor
timestamp: April 17, 2021, 03:49:21 am
content: My PCB manufacturer is still quietly teaching me how to make a PCB that is assembly-friendly. AFAIK, they always ask permission and show me a picture of the design changes they wan to make. And sometimes I learn and fix it myself next time. But by the next time, I often have forgotten about it.My poor manufacturer fixed soldermask openings on my boards for years before I remembered to do it myself and to prevent that conversation and save us both the hassle.

author: phil from seattle
author_rank: Super Contributor
timestamp: April 17, 2021, 05:06:42 pm
content: Quote from: KL27x on April 17, 2021, 03:49:21 amWell, that's good if you are learning. JLCPCB is always showing me problems with my boards that don't exist. Like missing pads that are clearly not missing. They show before and after gerbers that are identical. A bit comical at this point but the first time I saw it was a WTF!?! moment as I stared and stared trying find the problem.JLCPCB adds 2 things - an order number in the silk screen layer and 2 very small registration holes. You can tell them not to add the number and add the reg holes yourself, if you want. They do the obvious clean up stuff (silk screen on copper and such).

author: GerardG
author_rank: Regular Contributor
timestamp: April 19, 2021, 07:02:55 am
content: All board houses need to do etch compensation on the designs anyway, producing without it is no option.If you want to be absolutely sure there is no change on your file, you need to request the production gerbers and look at them in a gerber viewer.When the file has no etch compensation, you know it is no production file.The board manufacturer tries to optimize the board to minimize the scrap in production. The prototype PCB manufacturers can not put a lot of work in optimizing your files, they only run an optimization script or return your gerbers for you to change. When you pay $5 for the boards you can not expect them to put a lot of time into communications or loose time in checking multiple data sets (after modification).Even the bigger companies will optimize your board, but they know when to ask you if you are OK with the changes.So my 2 cents:To see the changes in your gerber ask for production files. (check for etch compensation)To make a board that can be produced you need to do your own DFM.