The Smart Group has produced a nice little set of images that seem suitable
for solder paste print acceptance criteria. As you suggest, direct
measurement of solder paste height is not one of the acceptance criteria.
Though, it may make sense to include height, if it can be measured easily
enough to be cost effective. Variation is the attribute of interest. If you
are getting 1 to 1.5 mil variation and start seeing 3 or 4 mil something is
up.


> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
> Sent: Wednesday, April 21, 2004 10:46 AM
> To: [log in to unmask]
> Subject: [TN] IPC standard on paste height?
>
> Hi Technos,
>
> the fact that paste height is maybe not a relevant and
> worthwile factor to measure has been brought up several times
> on this forum. My experience also says that I will have the
> same acceptable joints whether using a 6 mil stencil or a 5
> mil one, if the paste deposits are uniform (nice bricks). But
> if I write a procedure setting the control zone between 5.5
> to 8 mils I will get flamed by both the customers auditing
> the process and my bosses.
>
> Is there any standard/handbook/specification that sets
> control limits for the height of the paste after stencil
> printing? Or which prescribes other measurable indicators for
> good printing?
>
> I must mention that I only have an LSM that can measure the
> height, no volume checking available.
>
> Thanks,
> Ioan

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