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Examining Soldermask pads and Symbol Soldermask definitions.

lcan

No Venture license for Advanced DFx checking -  So, as a novice at SKILL I am writing a Soldermask check to look for padstacks that have inaccurate mask openings. I am further trying to see if "tented" padstack definitions are cleared by Symbol shape definitions on the mask layer(s) within the Symbol. However I am having trouble as I loop through each symbol pin - how do I find out if it has a mask shape above or below it?  I see the axlGeoPointInShape command, but I first have to get the shape.  I have gone through manuals, examples and publicly released code but my efforts have failed me.  What i've done so far isnt pretty but it works for the most part.... I'm doing testing with Place Bounds as a shape because I know all symbols have them, but I also know I am going at it wrong. Any help would be greatly appreciated. Thanks in Advance!

Bill

axlClearSelSet()
vis_list = axlVisibleGet()
axlVisibleDesign(nil)
axlVisibleLayer("PIN/TOP" t)
axlSetFindFilter(?enabled list("noall" "pins")
?onButtons list("noall" "pins"))
axlAddSelectAll()
pselect_list = axlGetSelSet()
axlClearSelSet()
axlVisibleSet(vis_list)

foreach(pin_db pselect_list
unless(pin_db->isMech ;must be doing it wrong - Mechanical pins still getting through
if(pin_db->isThrough
then
symbol_dbid = pin_db->parent
symbol_name = axlDbidName(symbol_dbid )
IsShape = pin_db->objType
shape_layer = pin_db->layer
if( equal(IsShape "shape") then
if( equal(shape_layer "PACKAGE GEOMETRY/PLACE_BOUND_TOP") then
println( "has a shape" )
);endif
);endif
location = pin_db->xy
tsm_pad = axlDBGetPad(pin_db "pin/soldermask_top" "regular")
cur_box = tsm_pad->bBox
tsm_box = tsm_pad->bBox
ComputeBBoxHeight( )
top_pad = axlDBGetPad(pin_db "etch/top" "regular")
cur_box = top_pad->bBox
top_box = top_pad->bBox
ComputeBBoxHeight( )
if(tsm_box == top_box
then
top_mask_same = "true"
else
println( symbol_name ); <-testing
println( shape_layer ); <- testing
);endif
bot_pad = axlDBGetPad(pin_db "etch/bottom" "regular")
cur_box = bot_pad->bBox
bot_box = bot_pad->bBox
ComputeBBoxHeight( )
bsm_pad = axlDBGetPad(pin_db "pin/soldermask_bottom" "regular")
cur_box = bsm_pad->bBox
bsm_box = bsm_pad->bBox
ComputeBBoxHeight( )
if(bsm_box == bot_box
then
bot_mask_same = "true"
else
println( location )
);endif
else
pin_type = "smd"
);endif
);unless
);foreach
);

procedure( ComputeBBoxHeight( )
bBox = cur_box
ll = car( bBox )
ur = cadr( bBox )
lly = yCoord( ll )
ury = yCoord( ur )
ury - lly

) ;procedure

Parents
  • B Bruekers

    I'm not entirely sure what you want to achieve, but perhaps this will help you:

    Each pin in the design has a definition: padstack. So if you need to check if a certain padstack contains a mask definition then just go over each padstack definition. This makes the initial check much faster. 

    In a small design it is 'ok' to iterate over all (user) mask shapes and test them with poly operations. But with a large board i would not do this, it takes too much computing time. 

    The best approach for doing such is something like this:

    1. Get all pins
    2. Get all user mask shapes (so not the ones defined in the padstack but on board or package geometry class)
    3. foreach pin determine if the pin bBox is overlapping with a mask shape bBox.
      1. Overlapping bBox does not mean that the shapes/figures are overlapping. To check this get the poly of the pin and shape.
      2. If you need a certain mask oversize then expand the pinpad poly with this value.
      3. Then do a poly operation on the padpoly and mask shape. By using 'AND you get a resulting poly. If everything is correct then poly area (property of the poly) is _nearly_ equal to the mask poly area. If area is smaller: then pad was smaller, or mask was larger then required.
      4. By doing an 'OR you can check if the resulting area is larger than the original mask area -> if so then the mask opening is too small.
      5. If you are programming it smart then remove the checked (and matched!) shape from the list so you don't check it against all remaining pins.

    Bram

  • lcan
    in reply to B Bruekers

    Thank you Bram!  I am going to attempt some of what you described here. I will post results for reference.  One of the errors I am trying to catch with this check are "tented" vias that are defined as Pins in a symbol which are supplied by Vendors that have inaccurate padstacks ie: not relieved of soldermask. The Vendor I am sure believes that a Soldermask shape solves the problem - however the padstack is still wrong and if used elsewhere.... So, I almost punted on this part of the check but these Vendor supplied symbols are happening more frequently, along with their errors. Your response has helped keep me moving in the proper direction, thanks!

    Bill

Reply
  • lcan
    in reply to B Bruekers

    Thank you Bram!  I am going to attempt some of what you described here. I will post results for reference.  One of the errors I am trying to catch with this check are "tented" vias that are defined as Pins in a symbol which are supplied by Vendors that have inaccurate padstacks ie: not relieved of soldermask. The Vendor I am sure believes that a Soldermask shape solves the problem - however the padstack is still wrong and if used elsewhere.... So, I almost punted on this part of the check but these Vendor supplied symbols are happening more frequently, along with their errors. Your response has helped keep me moving in the proper direction, thanks!

    Bill

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