T
treez
Guest
Hello,
I have just done a 4 layer PCB in Eagle Pro, and the PCB assembly house keep asking for "CAD Data" or "ASCII files", as well as the gerber files.
Anyway, i have no idea what "ASCII" files exactly refer to, so i sent them a "parts list" which i got by going to the layout window then going "FILE > EXPORT > PARTSLIST.
The PCB assembly house seem to accept this "parts list" as an acceptable alternative to an "ASCII file".
The file that comes out is as attached.
The numbers in the file , are actually the x,y coordinates of the component centre. But how does Eagle know where the component centre is?.....i didnt mark out a point in each component as being the centre when i drew them up in the footprint lbrary.
-However, for example with 0603 resistors, i did make sure that the (0,0) point was right in the middle between the pads.
Also when i draw the footprint, i dont pay attention to "rotation", because who is to say which is the zero rotation orientation?
So what use will the rotation data in the attached CAD file be?
What do you think the PCB assembly house use this data for?.......when i ask, nobody seems to know, they might speak to my boss, but they just seem to politely fob me off when i ask.
Also, i presume "MR" means "Mirror-then-Rotate"?
and "R" means "Rotate"?
Also, some of the components are SOT23, which has three pads, and its questionable as to where the centre of the SOT23 part actually is..........when i draw the SOT23 footprint, i always make the (0,0) coordinate of a SOT23 as follows....
-extrapolate a horizontal line and a vertical line out in both directions from the centre of each of the three pads.
-i then have a 12 square "oxo" board.
-i then get the "central square" which consists of the central two rectangles merged.
-The geometric centre of this rectangle is what i call the centre of the SOT23...and is (0,0) in the library footprint program.
....however, i have no idea if this "centre" is of any use to a pick n place machine?
Also, regarding the centre of a DPAK footprint.....where do "the standards" say that that is?
-with me , i just make it the geometric contre of what i call the "courtyard", which is a rectangle which encloses the pads as i have them in the footprint.
-But again, is this any use to a pick and place program?.....and do you know what i should do for rotation?
Also, why is this file so useful to the PCB assemblers?, so useful that the gerbers alone are not seen as sufficient?
I have just done a 4 layer PCB in Eagle Pro, and the PCB assembly house keep asking for "CAD Data" or "ASCII files", as well as the gerber files.
Anyway, i have no idea what "ASCII" files exactly refer to, so i sent them a "parts list" which i got by going to the layout window then going "FILE > EXPORT > PARTSLIST.
The PCB assembly house seem to accept this "parts list" as an acceptable alternative to an "ASCII file".
The file that comes out is as attached.
The numbers in the file , are actually the x,y coordinates of the component centre. But how does Eagle know where the component centre is?.....i didnt mark out a point in each component as being the centre when i drew them up in the footprint lbrary.
-However, for example with 0603 resistors, i did make sure that the (0,0) point was right in the middle between the pads.
Also when i draw the footprint, i dont pay attention to "rotation", because who is to say which is the zero rotation orientation?
So what use will the rotation data in the attached CAD file be?
What do you think the PCB assembly house use this data for?.......when i ask, nobody seems to know, they might speak to my boss, but they just seem to politely fob me off when i ask.
Also, i presume "MR" means "Mirror-then-Rotate"?
and "R" means "Rotate"?
Also, some of the components are SOT23, which has three pads, and its questionable as to where the centre of the SOT23 part actually is..........when i draw the SOT23 footprint, i always make the (0,0) coordinate of a SOT23 as follows....
-extrapolate a horizontal line and a vertical line out in both directions from the centre of each of the three pads.
-i then have a 12 square "oxo" board.
-i then get the "central square" which consists of the central two rectangles merged.
-The geometric centre of this rectangle is what i call the centre of the SOT23...and is (0,0) in the library footprint program.
....however, i have no idea if this "centre" is of any use to a pick n place machine?
Also, regarding the centre of a DPAK footprint.....where do "the standards" say that that is?
-with me , i just make it the geometric contre of what i call the "courtyard", which is a rectangle which encloses the pads as i have them in the footprint.
-But again, is this any use to a pick and place program?.....and do you know what i should do for rotation?
Also, why is this file so useful to the PCB assemblers?, so useful that the gerbers alone are not seen as sufficient?