If your pad geometry does not yield at least .1mm solder mask sliver
between pads, they will want gang opening, obviously if you use a gang
opening it will remove the minimum solder mask sliver from
consideration, so most fab shops will prefer the ganged opening, the
real question is what do the assy people prefer?
.5mm centers - .1mm SM sliver = .4mm - .1mm SM oversize = .3mm pad width
.4mm centers - .1mm SM sliver = .3mm - .05mm SM oversize = .25mm pad
width
As you can see, at .5mm it is possible, at .4mm that .05mm oversize is
the killer, .075 is the least I've heard that a shop will reliably do
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Oommen Mathews
Sent: Monday, February 02, 2004 7:26 AM
To: [log in to unmask]
Subject: [DC] Regarding Solder Mask Preference
Hi.,
For fine pitch QFP and SOP components (.5 mm or less) which type of
solder mask is preferred in a fab point of view ? Gang solder mask or
individual pin/pad mask ?
regards,
Oommen Mathews
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Hosur Main Road,
Bangalore - 560 100. India
Tel:+91 (0)80 8520408 Ext:4132
Res:+91 (0)80 6659004
email: <[log in to unmask]>
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