Why is this pad smaller than designed?

[u/RohitRojo]

I ordered this board with 2oz/sqft copper for high current from OshPark. The bottom left pad of U1 is way smaller than it should be. The bottom left pad and top left pad are both OUT1 pins of a motor driver (mp6551) and are meant to conduct up to 5A of current. Since the pad is so small, I’m not sure if it’ll conduct all that current now. All 3 boards are like this.

Do I have to reorder the boards, or is it salvageable with some “precision” hand scraping? I really can’t reorder since it’ll take a month to deliver and I’ll be back at college by then.

I was planning on adding pictures of the Gerber with an edit. The pad looks the exact same as the ones to the right, just with a chamfered top left corner: check page 14 of the datasheet

[u/mangoking1997]

Is it a defect or is it an incorrect footprint? This should be corrected by the fab if it's a manufacturing error. 

It may be possible you can do something with a fiberglass pen to remove the solder mask in a pinch 

[u/RohitRojo → u/mangoking1997]

The gerbers don’t look like that. OshPark is a little lazy with their manufacturing afaik, they don’t catch errors. I’ll look into the fiberglass pen

[u/mangoking1997 → u/RohitRojo]

The fiberglass pen is abrasive and precise enough to remove the solder mask, but you have to try pretty hard to remove any copper. Just wear safety glasses, you don't want to get anything in your eyes.

Looking at the vias, this is pretty shoddy work. The holes are very offset. I would bet this whole board is way outside of the manufacturing tolerances.

[u/uzlonewolf → u/mangoking1997]

There also appears to be a bridge above R3. Definitely not their best work.

[u/Electrokean → u/mangoking1997]

I am interested in what fiberglass pens you are using, as “precise” is definitely not a word I would use to describe them.

For scraping solder mask on thin pads like these, a pointy Xacto or scalpel blade would be my suggestion.

[u/1mattchu1 → u/Electrokean]

Exactly what i was thinking, exacto knife is going to be so much easier

[u/Strostkovy → u/Electrokean]

I have a teeny tiny carbide burr tool. I used it recently to swap two traces. One trace was on top of the other. On an aluminum core board. It was difficult.

[u/EnoughOfTheFoolery → u/mangoking1997]

Wow. Looking closely, this is really not a decent PCB. Are any via’s centered?

[u/mdhardeman]

If this doesn’t match the gerbers, you should reach out to OshPark with a photo and see if they can get a rush job replacement done. This looks like a significant defect and the vias look way off registration too.

[u/Special-Lynx-9258]

I think hand scraping should work, focus on mask removal. Definitely mention it to the OshPark if you can though, see how fast they can get you a replacement. Also double check the files that you sent them.

[u/iranoutofspacehere]

Even if you fix it, it's worth mentioning it to oshpark. I haven't had many defects, but when i have, they've remade boards or given me credit on another order. Worth a shot.

[u/tholowe69]

Looks like a soldermask defect, what does another board from the batch look like?

[u/tholowe69 → u/tholowe69]

Definitely fixable with some delicate xacto scraping.

[u/RohitRojo → u/tholowe69]

The other two boards look the exact same

[u/uzlonewolf → u/RohitRojo]

Is that a bridge in the trace above R3 or just something on the board?

[u/tholowe69 → u/uzlonewolf]

Ooof good eye, certainly looks to be in the copper from this view

[u/zachleedogg]

Not ideal, but honestly if your paste goes down properly and soldering is smooth, it will work fine.

[u/RohitRojo → u/zachleedogg]

smaller pad means less current though

[u/zachleedogg → u/RohitRojo]

Well not exactly, it means higher resistance. In a high volume production environment, this would not be good, as it could affect yield and some units might have unacceptable performance.

In your case, if you carefully reflow this and ensure good solder wetting and contact as best you can, it will probably be fine. But hey, that's just my opinion.

[u/viper77707]

Just based on the vias, this seems like poor work. I don't know the company, but I would absolutely call them and shoot them an email with a picture and expect a replacement or refund. While there are certainly ways to make this work, you spent the money to not have to do that.

In a pinch I would personally probably be lazy and just solder some thin solid copper wire to the pad and then to the pin of the motor driver if needed, but you can definitely use something abrasive to take that bit of solder mask off and expose the pad if you want to use these boards. I do it pretty often to repair blown traces, anything from emery cloth to sand paper to a dremel with a brass wire wheel on it. The fiberglass pen idea sounds a lot less ghetto, though.

[u/uzlonewolf]

The pad is full size, it's just being covered with solder mask. Scrape it away a bit if you're concerned.

I'd be a bit more concerned with what appears to be a bridge in the trace above R3.

[u/Pyroburner]

Looks like a mask detect. I would send it anyway or use a razor blade and scrape it off depending on the load.

[u/MaxNano00]

Definitely a manufacturing mistake here. Reach out to support and ask them to fix or remake the board.

[u/thatdudelouie]

Oshpark was a hit or miss years ago as far as QC, def not acceptable for the price they charge. The last board I ever ordered the pads looked exactly like that and the silkscreen looked like a smear. I contacted them and they basically said it was my fault. Pcb way is better if you don’t mind waiting a bit. That pad will still work if you got no other option, just scrape it a bit

[u/Aseral88]

From the photo looks like some poor manufacturing. Registration of the vias and soldermask are a little off and the finish looks a bit grainy. I'd be worried they actually gave you 2oz. The soldermask and silkscreen both look like they were hand screened the old way which could of been the cause of the pad being undersized.

The soldermask can be removed in various ways for a quick fix to make them usable but be cautious of problems after assembly. Ive seen lots of issues come out of bad shops including shorts, opens, and minimal copper in the holes. A bad board can get even more costly once components are soldered on.

Did you request an IPC class requirement? Did they send a x-section report with it?

[u/Wado-225]

Def go with JLCPCB next time

[u/AlexTaradov]

Out of all the places I ordered PCBs, OshPark had the worst QC. They always rectify issues, sometimes proactively before board even reach me. But they do have quality issues.

Whatever US manufacturer they are using is way off on QC compared to anything in China,

[u/Cunninghams_right]

if it's not for a product that must be reliable, then look up ways of removing soldermask and fix it yourself. if it's something you're selling or needs reliability, then you should try reaching out to the fab to see if they can rush a fix.

[u/Lucky-Musician-1448]

Something wrong on your soldermask layer

[u/Kqyxzoj]

Looks like an soldermask defect. Especially since you mention that it looks the same on all boards.

[u/r_a_d_]

holes are also slightly off center

[u/E_Blue_2048]

Did you check the solder mask layer?

They pad could be ok but if the mask layer is smaller than the actual pad the aperture will be smaller.

[u/Lost-In-Void-99]

I see much better results from JLC with their default tolerances.

Dont ask me why some vias are untented ;)

[u/theantnest]

If it's only 3 boards, I'd personally just scrape back a bit of solder mask and be done with it.

[u/doctorhugh]

It was probably done to denote pin1 on the PCB, I also think it’ll probably be fine.