SparkFun Forums

[Chip Douglas]

Ive been using eagle for years and ive never ran into this problem:

For some reason my traces are not aligning center of the pads on the tsop device in my layout.When i zoom in they are perfectly center, but as soon as i click the fit button the traces shift to either the right or left of the pads.Because the pitch is so small to begin with (0.5mm) even the slightest shift is not acceptable.At first i thought maybe it was a glitch, so i printed it out and it was still out of alignment.Ive used tsop footprints before and never had this problem, and i havent changed any settings in eagle.

Im hopeing someone else may have ran across this problem and figured out the problem, and could help me out.

[Philba]

that's probably because you are routing off grid. Unavoidable. But if you start the traces at the off grid pads, you shouldn't have that problem.

[Chip Douglas]

that's probably because you are routing off grid. Unavoidable. But if you start the traces at the off grid pads, you shouldn't have that problem.

Im not so sure thats the problem.The pads on the tsop footprint line up center between the grids,i made sure of that before routeing the wires.It seems it does this when i zoom in or out to a certain percent.I reinstalled eagle and redid the board layout and seem to have fixed the traces, but ive noticed that now the pads arent equally spaced apart when i click the fit button or printed out.I cant understand this.Why would some of the pads be spaced closer together then the others, when its obvious they should all have a 0.5mm pitch.This is a premade library that comes with eagle.Its in the st-microelectronics package.Its like its some weird aspect ratio problem like when you resize a picture and it looks all distorted.But if it was my monitor that is causing the pads to show up "out of pitch" then when printed out it should be normal, but it prints exactly as shown on screen.

I really dont know how else to explain this so i will export this to image and post it shortly.

[Philba]

From your explanation, I'm not sure what you are seeing. I have seen cases where you zoom out in board view and things move around a bit on the screen but if you print it out 1:1, it looks correct. Does it only happen with that one part or any tsop?

[Chip Douglas]

From your explanation, I'm not sure what you are seeing. I have seen cases where you zoom out in board view and things move around a bit on the screen but if you print it out 1:1, it looks correct. Does it only happen with that one part or any tsop?

As far as i know it only happens with that tsop footprint.And i couldnt find any other eagle libraries with a 48 pin tsop.I really dont understand why it does this.I even went as far as making my own library by editing the pads to make them thiner just to see if i could compensate for the spacing problem.I do alot of prototyping boards that i etch by hand, and 0.5mm pitch is the smallest pitch i can do.So when some of the pads end up being 0.4mm or less, they just end up bridging together.Im going to test rotating the footprint and see if it still does it.Right now my layout calls for the footprint to be horizontal, but i'll placing it vertical.