I want to know about the SMT requirement documents. what I mean is that

when I make a partlist and XY-coordination data from PCB software. that shows me rotation angle like R90 or MR270 I know that R90 means rotate it 90 degree and MR270 is mirror and rotate parts. enter image description here

but I'm curious how to know the direction? R90 can be either clockwise or counterclockwise? and I think If the pin position is opposite, so it may cause confusing.

For example, If I make a capacitor which is left to right pin number are 1 and 2. but other people make a capacitor which is left to right pin number are 2 and 1. those are opposite way.

In that case How the SMT manufacturer know the direction of parts?

(add one more picture for a question)

enter image description here

  • \$\begingroup\$ Gerber files contain all information regarding this \$\endgroup\$ – Sorenp Oct 24 '19 at 7:35
  • \$\begingroup\$ @Sorenp gerber files do not. ODB++ files do. \$\endgroup\$ – Jeroen3 Oct 24 '19 at 7:55
  • \$\begingroup\$ I added one more picture what I'm curious. Please help me out! Thanks \$\endgroup\$ – S.JIN Oct 24 '19 at 9:36

For components that have no polarity, like resistors and ceramic capacitors, the pin definition is irrelevant.

For components that do have polarity, like electrolytic capacitors, diodes, ICs, etc., you have to provide polarity information on the silk screen. For instance, draw a line on the silk screen next to the pad corresponding to a line in the component marking (typical in capacitors), use + and/or - symbols, write letters A and K next to the correspondent anode and cathode pins in a diode, etc. For ICs the convention is to mark the location of the pin 1 or A1 in case of a ball grid array. Through-hole ICs or connectors sometimes use a square pad for pin 1 and circular pads for the other pins.

If your board has no silk screen you have to provide polarity information in assembly drawings to clearly define the polarity of components that may present orientation ambiguity.

Based on this information, the production line technicians will properly program the pick-and-place machine to place these components correctly based on the orientation that they come inside the reel.

  • \$\begingroup\$ thanks for your kind. but If I draw footprint rotated for example, first pin is rotated in my footprint 90 degrees, then in the board, 0 degree is not the real 0 degree of the parts, because actually it is rotated in the footprint in that case how they can know? I think the 0 degree which has diversity of footprint because it can be varied for each people who is drawing footprint. I add one more picture for explain it. \$\endgroup\$ – S.JIN Oct 24 '19 at 9:26
  • \$\begingroup\$ You have to make sure that your footprint library is consistent with your schematic symbol library. Double-check everything. \$\endgroup\$ – joribama Oct 24 '19 at 17:22

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