2
\$\begingroup\$

I got a quick friendly critic from someone in production for the below trace that I should not route the trace from the edge of a pad. What he said that it would create an extra force to the trace that might cause problem especially for smaller pad size in the production.

enter image description here

I could not really clearly understand what is the problem. If there is a force in the trace direction, I can imagine that it may break the trace, but is it something may occur during the pick and place machine or is it an after production concern? Could anyone please help me to understand what kind of problem may occur and how likely is it to happen?

\$\endgroup\$
  • \$\begingroup\$ I'd be more worried about the weird angles you have showing there, than the fact that a trace leaves a pad at an angle. That's only something to worry about on very small packages. \$\endgroup\$ – Matt Young Dec 1 '14 at 13:33
4
\$\begingroup\$

Keep in mind that the solder mask will be expanded by some mils (the exact number depending on the manufacturing process you're designing for) around the pad so you'll get an asymmetric pad shape that will tend to pull the package. Probably not a big deal, but it also looks ugly. If you had a bunch heading off in the same direction (or, worse, antisymmetric on top and bottom rows) it might become an issue- symptom would be a rotation of the package during the soldering process.

The same trace seems to bend unnecessarily close to the left pad and is at an angle close to horizontal but not quite- try to maximize clearances and keep almost-horizontal traces horizontal. A 45 degree snap on angles works well for most purposes.

\$\endgroup\$
0
\$\begingroup\$

"Unusual" geometry (which is a relative term, of course), can result in less effective inspection by humans and machines -- since a 'false positive' may be created; the more of these you have, the less likely a real issue may be noticed.

\$\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.