Got some boards back that were not made to specs. Here is a thought that may help others in the future. I was using jlpcb. After you are prompted to pay for your board, there is a recommended pay now and an option to preview the board after ten minutes or something. Choose the preview option and compare. Good Luck.
Whose specs, yours or theirs? Remember that they give their capabilities and recommendations. Unfortunately they sometimes (not necessarily predictably) changes something to fit for their capabilities, or if they think you have underspecified or think you made a mistake. And not all changes are visible in the preview.
We once received a small batch where we had some small Solder Mask Defined pads. It looked like they had manually scraped some of them larger, but not identically in all boards. They are the cheapest of the well known manufacturers, and you get what you pay.
2 Likes
There were missing pads. I guess that was ?? specs. Their CAD showed the pad exposed as per my specs but it was covered on the PCB. I have looked at other suppliers and from what I can tell, they too out source and then cut the boards apart upon arrival in my home country USA. It then requires a few extra days for the second operations. I have used a US manufacture but several times their solder mask was off and that does no go well with SMD components. I ordered a new set today and if all goes well, I will get then on Friday/Saturday.
I had that happen too with another manufacturer, they sent me fixed boards for free.
I think frequent source of error here is that kicad default mask expansion is too high and manufacturers manually reduce it when in their pre-prod processing. This sometimes leads to some pads being covered up because their software is buggy.
My advice is to get the solder mask expansion value they recommend and set it in kicad before generating gerbers so that they don’t have to do it for you and add errors.
5 Likes
The KiCad default mask expansion used to be TERRIBLY EXCESSIVELY LARGE. Many of my earlier posts were in regard to just setting the expansion to ZERO.
I have never know what the core reason for the prior KiCad default mask expansion was. It has always been my personal opinion that you state what you want in your design files, and you get back the manufactures +/-% production tolerances are. And, you design around what your own design tolerances are.
For “NORMAL” footprint pads, both THT and SMD, I can think of no good reason to NOT set the soldermask expansion to anything other than ZERO.
Maybe the idea was for KiCad to provide a default that worked with a specific manufacture?
Bold claim. You could have included the files you sent out, as well as photos of what was made wrong… and, you did not.
Doesn’t that company participate in the forum? They have seemed reasonable in the past.
This is exactly why we encourage meaningful and relevant vendor participation.
1 Like
Well, he did not mention if he contacted the manufacturer, I have had stuff like that happened to me in the past (not only with jlcpcb), however, every single time when i pointed it out, they redid the PCB at no extra cost.
That’s weird. I’ve had one problem with their solder masks, but that problem was a bit different than yours.
JLCPCB’s spec sheets don’t give details of their solder mask limitations. It appears that if your solder mask apertures are too small, or maybe too close together, your pads end up covered.
I created a footprint for a TI TPD4F003. It’s a tiny little device, measuring only 1.80mm x 1.45mm, with pads on 0.40mm centers. Here is a screenshot of this footprint in the KiCad PCB editor. For reference, the larger pads below it are on 2mm centers.
This was my first order from JLGPCB. The final board was to be four layers, but I wanted to verify I’d placed the mounting holes properly and some other characteristics before paying for a four-layer PCB. So before I finished the routing I ordered a two-layer board with just the outer two layers. Here’s a photo of the resulting PCB.
There are no openings for this device’s pads, while the vias and the large pads below it are properly exposed and ENIG plated. It’s kind of hard to tell because of the glare, but all the tracks are covered.
Before ordering the final four-layer board I widened the solder mask apertures for this device. The solder mask ended up with two rectangular cut-outs over the pads (one on each side). This is the same as on the other fine-pitch (0.50mm) devices.
JLGPCB really needs to give proper specifications for their solder mask capabilities so we don’t submit Gerbers for boards they can’t make. And their CAD checks should flag solder mask problems. But once you understand their capabilities and limitations, they seem to produce a good quality product.
2 Likes
I’ve made tons of boards through JLCPCB, and I’ve never had a problem. However, I usually use THT components, and when I do use SMT, I use large components (0805 passives, and SOIC chips).
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.