At 06:57 PM 3/3/01 -0500, Duane Hague wrote:
>For example, on QFPs the same manufacturer will refer to a part as having 
>a 25 "mill" (0.025 inch) pin pitch and then provide a package drawing in 
>metric showing a pitch of 0.65 millimeters "Typical" (and the other 
>dimensions on the drawing indicate that the original was in "inches" and 
>then converted to metric).

That's a drawing or reading error. The drawing should state that the 
[metric, imperial] system is controlling. However, some parts are on 25 mil 
pitch, I think, but .65 mm is definitely common.

Yes, 25 mils is not .65 mm, and this is not roundoff error, since 25 mils 
to two places is .64 mm, not .65. But it is exactly .635 mm. Perhaps there 
are some cumulative dimensions on the drawing that will give you a clue as 
to the actual dimension.

Most parts, especially newer QFPs, are now drawn in metric, in my 
experience. I'm betting on .65 mm.

[EMAIL PROTECTED]
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433


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