If the clinch, or solder fillet formed on the lead, violates minimum
electrical spacing it is a defect. The short story is that the space needs
to be more than .13mm for applications with less than 100 volts between the
lead and the conductor when the assembly is coated as you have described.

Assuming a PTH, the lead clinch should be partial, only enough to retain the
component during handling prior to soldering (between 15°and 45°). The lead
clinch should not extend beyond the diameter of the anular ring around the
hole. The PTH diameter must be specified to allow the assembly process to
meet these requirements. The PTH diameter should be between 0.2mm and 0.7mm
greater than the lead diameter. The closer to 0.2mm the less trouble with
clinch and the more trouble with auto insertion.

Some designs create problems by using very small rings and placing
non-common conductors in close proximity to the undersized rings. In the old
days, only a few years back, I specified dry film solder mask on board
desings that had such compromises. That may not be possible today, dry film
photo imagable mask is not popular and most fabricators are not maintaining
the equipment needed to apply the mask.

Wish I could be more help.

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of [log in to unmask]
> Sent: Monday, May 20, 2002 5:36 PM
> To: [log in to unmask]
> Subject: [TN] assembly spacing
>
>
> I have a component lead that is clinched on the bottom and the
> lead is almost
> touching the surface of a conductor.  Good old 001C says that the
> oreintation
> of the clinch relative to any conductor is optional.  However, it appears
> that direction is causing the problem.  Of course the assembly is
> conformal
> coated and it is nearly impossible to determine the exact spacing from the
> surface.
>
> Are there other guidelines for this condition?
>
> Thanks for any info
> Susan Mansilla
> Robisan Lab
>
>

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