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default_smd was too big for low density boards

This commit is contained in:
dickelbeck 2009-11-13 14:37:37 +00:00
parent 5fce2dc71c
commit 3da78c5da1
1 changed files with 9 additions and 3 deletions
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12
pcbnew/specctra_export.cpp
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@ -993,14 +993,20 @@ void SPECCTRA_DB::FromBOARD( BOARD* aBoard ) throw( IOError )
sprintf( rule, "(clearance %.6g)", clearance+safetyMargin ); sprintf( rule, "(clearance %.6g)", clearance+safetyMargin );
rules.push_back( rule ); rules.push_back( rule );
// On a high density board, a typical solder mask clearance will be 2-3 mils. // On a high density board (a board with 4 mil tracks, 4 mil spacing)
// a typical solder mask clearance will be 2-3 mils.
// This exposes 2 to 3 mils of bare board around each pad, and would // This exposes 2 to 3 mils of bare board around each pad, and would
// leave only 1 to 2 mils of solder mask between the solder mask's boundary // leave only 1 to 2 mils of solder mask between the solder mask's boundary
// to the edge of any trace within "clearance" of the pad. So we need at least // to the edge of any trace within "clearance" of the pad. So we need at least
// 2 mils *extra* clearance for traces which would come near a pad on // 2 mils *extra* clearance for traces which would come near a pad on
// a different net. So if the baseline trace to trace clearance was say 4 mils, then // a different net. So if the baseline trace to trace clearance was say 4 mils, then
// the SMD to trace clearance should be at least 6 mils. Also add our safetyMargin. // the SMD to trace clearance should be at least 6 mils.
sprintf( rule, "(clearance %.6g (type default_smd))", clearance + 2.0 + safetyMargin ); double default_smd = clearance + safetyMargin;
if( default_smd <= 6.0 )
default_smd = 6.0;
sprintf( rule, "(clearance %.6g (type default_smd))", default_smd );
rules.push_back( rule ); rules.push_back( rule );
/* see: http://www.freerouting.net/usren/viewtopic.php?f=5&t=339#p474 /* see: http://www.freerouting.net/usren/viewtopic.php?f=5&t=339#p474