I am trying to confirm the right orientation for all the packages I am using in Eagle before sending for pick and place assembly. After reading a bit, I understand that there is no standard from one chip company to another.

My question is simple: can I know for sure the proper orientation based on the way the chip is positioned in the reel ?

SOT25 package I want to know rotation 0 orientation

Looking at the way leds are packaged, and knowing that rotation 0 for leds is cathode on the left and anode on the right, I would tend to think that I can get the rotation 0 orientation by looking at chip with the holes on the left: is that correct ?enter image description here

  • \$\begingroup\$ By and large, don't worry about it. As long as all your rotation values are consistent for each component (e.g. all 0603 resistors use same rotation origin), the assembly house will deal with ensuring correct rotation. \$\endgroup\$ – Tom Carpenter Mar 16 '18 at 19:57
  • \$\begingroup\$ I know that there is a check by manufacturers and that they will manually correct rotation or position issues. I would feel more comfortable to know there is minimum manual intervention the day I go in production for a large batch. \$\endgroup\$ – AlexP Mar 16 '18 at 20:37
  • \$\begingroup\$ They are used to fixing all this stuff and it will be built into your setup fees or lot price. Put your effort into minimizing the number of distinct footprints (affects setup) and distinct components (affects the number of feeders). If you can use two 10K resistors rather than one 4.7K and one 10K (without significant compromise) it is better. \$\endgroup\$ – Spehro Pefhany Mar 16 '18 at 23:42

It's also worth considering the direction the board passes through the pick-and-place/wave solder line. In my experience, the pick-and-place programmers can handle the part rotation issue when they set up their programs.

However, ICs, especially those with fine pin-pitch, should generally be sent through the wave solder process with pins perpendicular to the wave. Otherwise, solder bridges between pins are much more likely to form, ruining your PCB assembly or setting you up for lots of rework.


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