PCB fabrication preferences

Help Support GroupDIY:

JMan

Well-known member
Joined
Oct 26, 2019
Messages
503
Location
Midwest, US
I recently got my first ever pcbs manufactured, with loads of helpful input from forum members. I made a line amp board and a couple simple adapter boards. I used jlcpcb and I was quite happy with how the boards turned out!

Now I'm looking at a more complex circuit (a compressor, +/-28v and -- I believe -- roughly 90mA current draw from the PSU, which is separate). I'm wondering if you all have preferences about some of the specs when getting a board manufactured for [non-commercial] use in one of your builds -- HASL vs ENIG, 1oz vs 2oz copper, 1.6mm vs thicker boards, etc. I know that these variables all have their pros and cons in a given application and I've done a little research on them, so I'm not asking you to prescribe anything for my board per se, just wondering if you have any strong feelings or "safe bets" or what-have-you. Any thoughts are welcome!
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
14,554
Location
Norfolk - UK
I only used 2oz copper once on a motherboard carrying heater current and I bused the tracks on both sides of the board. I used 3.2mm thick board for that same project because there was a large unsupported area that other boards would plug into and I was concerned about its mechanical strength. Turns out I need not have bothered doing either.

I normally specify HASL but ENIG is easier to solder so I use it for paying clients.

I have had problems with poor quality silk screen from several Chinese manufacturers so I now get my board made either in India or Germany.

If you are using extensive ground planes you really need to put them on both sides of the PCB. This has nothing to do with improving grounding. If you flood one side of the board and not the other then there is a chance it will visibly warp.

Cheers

IAn
 

JohnRoberts

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Nov 30, 2006
Messages
23,278
Location
Hickory, MS
1oz copper is adequate for typical audio projects. Unless you are using the PCB for mechanical support thin PCB stock is also adequate.

There are multiple inexpensive PCB fab houses in china, remarkably cheap... The last time I tried to buy PCBs from a fab house in canada to avoid Chinese fab, my PCBs arrived shipped from China. :rolleyes:

JR
 

Newmarket

Well-known member
Joined
Oct 10, 2016
Messages
1,166
Location
Brighton Sussex UK
1.6mm FR4 / 35um/1 Ounce Cu / ENIG (although HASL is fine too)
For your circuit (and the vast majority of all circuits) there's no advantage in going "non-standard".
2 layer vs 4 layer is a much more important consideration.
Silk Screen registration can be important esp if small type but that is hard to specify.
 

swpaskett

Well-known member
Joined
Jun 2, 2021
Messages
85
Location
Mesa Arizona
I have used Aisler a number of times. They seem to have contracts with fabs in many countries. I am in the US and boards have shipped from Texas. The quality has been excellent, but check the design rules.
You may need to increase the minimum track width as I had one board with opens where I allowed the minimum. That is one of the gotchas -- any shorts or opens are your problem, even if the design rules they provide are wrong. Unfortunately, things like minimum track width are partly a property of the fab and you do not know ahead of time who is going to bab your boards. I found that 0.12mm was too narrow, but 0.15mm works consistently well.
Boards are priced by the square cm. There is no charge per hole or profile routing strange shapes, but they do charge to route out areas inside the board outline.
They require a minimum purchase of 3 boards, at least for the small boards I order.
That's all I am aware of; maybe Ian has other things in mind.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
14,554
Location
Norfolk - UK
Thank you. What sort of things?
First one is I have always included the board outline in the copper layer Gerbers as it allows the copper to be aligned to the board. This has never been a problem with any manufacturer until Aisler. Their process leaves a tiny copper track all around the periphery of the PCB if you include the board outline in the copper layers which tends to peel off and short things out. So you have to leave out the board outline in copper layers just for them. It is an easy fix but you need to be aware of it.

The second has no solution yet. They make all your boards as breakouts from a larger one. This means there is one or more tiny protrusions on each edge of the board where it was broken out from the bigger one. This is OK for many prototype boards but a real PITA for any plug in board that has to fit card guides. You have to go round manually with a file to get rid of them. Again this is something I have never experienced with any other PCB manufacturer. In discussion with them it turns out their process does not yet have a V-cut capability which is what would be required to make smooth edges.

Cheers

Ian
 

warpie

Well-known member
Joined
Feb 7, 2009
Messages
1,415
First one is I have always included the board outline in the copper layer Gerbers as it allows the copper to be aligned to the board. This has never been a problem with any manufacturer until Aisler. Their process leaves a tiny copper track all around the periphery of the PCB if you include the board outline in the copper layers which tends to peel off and short things out. So you have to leave out the board outline in copper layers just for them. It is an easy fix but you need to be aware of it.

The second has no solution yet. They make all your boards as breakouts from a larger one. This means there is one or more tiny protrusions on each edge of the board where it was broken out from the bigger one. This is OK for many prototype boards but a real PITA for any plug in board that has to fit card guides. You have to go round manually with a file to get rid of them. Again this is something I have never experienced with any other PCB manufacturer. In discussion with them it turns out their process does not yet have a V-cut capability which is what would be required to make smooth edges.

Cheers

Ian

I see, thank you very much. Overall, besides the silk screen issues, have you find the quality to be superior comparing to the Chinese fab houses or it's more of an ideological choice for you?
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
14,554
Location
Norfolk - UK
I see, thank you very much. Overall, besides the silk screen issues, have you find the quality to be superior comparing to the Chinese fab houses or it's more of an ideological choice for you?
I would call it a pleasant surprise! I bought all my PCBs from China for many years but their ongoing poor human rights issues finally persuaded me to vote with my feet. I initially transferred production to India and I immediately noticed an obvious improvement in quality which was repeated at Aisler. There are suppliers of Chinese manufactured PCBs that are able to monitor and improve PCB quality. I have used a couple of them and the resulting PCBs are much better than the likes of jlpcb and allpcb but you do pay a premium for them. The two I have used are listed below:

Techbridge Circuits

Quick Teck

Cheers

Ian
 

JMan

Well-known member
Joined
Oct 26, 2019
Messages
503
Location
Midwest, US
First one is I have always included the board outline in the copper layer Gerbers as it allows the copper to be aligned to the board. This has never been a problem with any manufacturer until Aisler. Their process leaves a tiny copper track all around the periphery of the PCB if you include the board outline in the copper layers which tends to peel off and short things out. So you have to leave out the board outline in copper layers just for them. It is an easy fix but you need to be aware of it.

The second has no solution yet. They make all your boards as breakouts from a larger one. This means there is one or more tiny protrusions on each edge of the board where it was broken out from the bigger one. This is OK for many prototype boards but a real PITA for any plug in board that has to fit card guides. You have to go round manually with a file to get rid of them. Again this is something I have never experienced with any other PCB manufacturer. In discussion with them it turns out their process does not yet have a V-cut capability which is what would be required to make smooth edges.

Cheers

Ian
This is good to know. So with Aisler the board outline should be kept to another layer like (in Eagle, for example) Dimension? This is actually what I had done on the recent batch of boards I had made, but it's always good to make note of these sorts of things.

Lucky for me, I don't need perfectly smooth edges for my current project, so those little mouse bites won't be a problem, although I can certainly see how they would be inconvenient in some applications (especially having to file them down on a whole bunch of boards).

I think I'm going to give Aisler a try. They aren't that much pricier than jlcpcb relative to some other places, and I agree with you wholeheartedly on the questionable ethics of ordering from China.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
14,554
Location
Norfolk - UK
Just to be clear, I do include a separate board outline file in my Gerbers. It is just that the PCB software I use has the option to also include the board outline in the copper layers. In the very early days (more than 10 years ago) I read or was told to include it this way and have done ever since because it never caused a problem and I assumed it was in fact necessary. The I used Aisler!

Don't get me wrong, Aisler boards are generally first class. I know how to aviod the copper outline issue and Aisler tell me they will be looking into offering V-cut. Their prices are not much more than the Chinese and I would much prefer to buy in Europe.

Cheers

Ian
 

JMan

Well-known member
Joined
Oct 26, 2019
Messages
503
Location
Midwest, US
Ah, understood. Okay, so from my perspective (as someone who wasn't including the outline in the copper layer already), if using Aisler I just won't change anything. Easy enough!
 

JMan

Well-known member
Joined
Oct 26, 2019
Messages
503
Location
Midwest, US
That was a very interesting read. Thanks for sharing!

It certainly makes me think that in my current situation, the tolerances need not be terribly strict, as I'm wastefully allowing a little extra board space between the outermost traces/components and the actual board edge (and I also do not have stringent dimension requirements for fitting into a tightly designed physical space), so in this instance the fab house could probably be off by even a few 10s of mils and it would not hurt anything.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
14,554
Location
Norfolk - UK
That was a very interesting read. Thanks for sharing!

It certainly makes me think that in my current situation, the tolerances need not be terribly strict, as I'm wastefully allowing a little extra board space between the outermost traces/components and the actual board edge (and I also do not have stringent dimension requirements for fitting into a tightly designed physical space), so in this instance the fab house could probably be off by even a few 10s of mils and it would not hurt anything.
Yes, it is definitely application dependent. Many of my boards are standard Eurocard size and must be able to plug in smoothly to standard sub-rack so the mechanical dimensions are critical. On the other hand, because of the card guide, you don't want tracks within 2.5mm of the board edges so there are no traces near the board edges.

What surprises me more than anything is that there seems to be no standards for this.

Cheers

ian
 

john12ax7

Well-known member
Joined
Oct 15, 2010
Messages
2,103
Location
California, US
I've had that same issue with 500 series when the route is not smooth. It messes up the mechanical alignment and mating. My particular boards were from OSH park, everything else was good otherwise.
 

Latest posts

Top