Aric,

Our TO-92 pad style is 0.064" by 0.100" long, oval in design, which allows for single sided punch & crunch
boards with no hole breakout.  We also try to design so that the pads will not go through the wave across
the pads for example:


wave direction -------->      O O O    (pads)    This is a no-no


wave direction -------->       O    (pads)  This is correct.
                                             O
                                             O

Let me know if you need other suggestions on this.  If so, let me know if you are using auto insertion
equipment for this and if so the manufacturer.



Mark Ross
Sr. Design Engineer
Whistler Auto-Mation
Novi, Michigan




Aric parr wrote:

> I have a problem with TO 92 transistor leads shorting during wave solder.
> They are radial inserted with a 45 degree clinch. The short is between the
> two leads clinched in the same direction. Rotating the board 180 degrees
> reduces the problem, but other layout issues make this impossible (shorts
> appear somewhere else). We cannot change the clinch direction. Wave
> parameters were adjusted within available limits (between reflowing top
> side smd during wave soldering and thermal shocking the chip caps on the
> bottom). Wave height was adjusted between flooding and unsoldered SMD. Very
> little effect.
>
> Does anyone have any suggestions as to pad design, hole design, wave solder
> adjustments, clinch geometry... that I can try?
>
> ARIC PARR
> Sr. Manufacturing Engineer
> Eaton Corp
> 1400 S. Livernois
> P. O. Box 5020
> Rochester Hills, Mi 48308-5020
> [log in to unmask]
> 248 608 7780
> Fax: 248 656 2242
>
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