0
\$\begingroup\$

I am stuck on a problem while working with eagle. I have to design a pcb which has large exposed pads on the top and bottom of the PCB. I had assumed that placing a tstop layer on the pad while designing it from scratch would have done the job.

However, when the PCBs were made, pads on the bottom side of the PCB were covered with solder-mask and are now useless. I have to now remove the solder-mask from them somehow.

Can anyone explain what I did wrong here please?

The image shows the bottom side of the PCB and I had placed tstop and bstop layers on the pads while making them. But they still ended up coated with solder mask. What went wrong?

enter image description here

\$\endgroup\$
  • \$\begingroup\$ How did you get the design to your manufacturer? Gerber Export? Check the generated gerbers for whether they actually match your design! \$\endgroup\$ – Marcus Müller Mar 29 '17 at 9:29
  • 2
    \$\begingroup\$ You should carefully inspect the PCB manufacturing data before sending them to the PCB fab. You could look at single layers in Eagle, especially the stop layers for top and bottom. But you should also use a Gerber viewer to look the fotoplot data. There are free gerber viewers available. \$\endgroup\$ – Uwe Mar 29 '17 at 9:32
  • \$\begingroup\$ Just drawing into bStop and doing a normal Gerber export works for me. And your screenshot looks OK. As Uwe said, check your data in a Gerber viewer. \$\endgroup\$ – CL. Mar 29 '17 at 10:52
  • \$\begingroup\$ Yes I used gerber export to send the files. I checked the data on the gerber viewer and sure enough the bottom pads were not showing somehow (I should have checked this before). I checked my design and the rectangle on the bstop layer was definitely there (pic above). As a last resort I just remade the part from scratch using the exact same process and NOW the gerber viewer shows the bottom soldermask perfectly. The new problem now is that I have the same soldermask on the top and bottom of the PCB even though the pad is only on the bottom. \$\endgroup\$ – Rhydo N Mar 29 '17 at 11:26
1
\$\begingroup\$

I have to design a pcb which has large exposed pads on the top and bottom of the PCB. I had assumed that placing a tstop layer on the pad

That will expose the pad on the top side of the board. If you also want the pad to be exposed on the bottom side you will also need to draw a box on the bstop layer.

Basically:

tstop = Top Solder Mask

bstop = Bottom Solder Mask

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.