(Just a tidbit… to keep you up at night)

 

We found a few errors in the IPC-2221 specification that need correction. (not that we were looking for them)

Note: This is also referenced in the CID design Guide on page 113.(it is wrong in both places of course, that’s where we found it first…)

 

We believe Table 9-1 page 74 of the design guide has a math error when converting from millimeters to inches… (don’t feel bad, NASA even has trouble with that sometimes)

Regarding manufacturing tolerances…

 

Note 1 says ‘add 0.05mm [0.0197 in.]  well… that is about 20 mils there isn’t it…?  Some how that raised a flag… do they need 20 mils for mfg tolerances?

Shouldn’t it say… ’add 0.05mm [0.00197] ? (with two zeros following the decimal point) that would be closer to the 2 mils I think they meant.

 

The same is true in the table Note 2… where they convert the same way…

 

 

Also at Section 1.6.3 mentioned in note 3, I went to that section in the IPC-2221 to read about the Producibility levels and found…(see page 3)

(I was still trying to make sense of note one and two)

 

3 producibility levels:

 

Level A General Design Producibility - Preferred

Level B Moderate Producibility - Standard

Level C High Producibility - Reduced

 

‘High’ producibility (in English) implies that the board is very producible when in fact it should be referencing the ‘least’ producible condition… or MOST DIFFICULT to produce.

It seems the terminology that was used earlier in the spec at 1.6.2 was somehow incorporated into this description when it should not have.

 

Perhaps it should read Level C Low Producibility – Reduced…?

 

That’s my contribution for this year… I’m done. (Can I go home now?)

J

 

Thank you all for the great responses… I got it.

J

 

Does someone have Rick Hartley’s phone number?

I want to talk with him for a minute or two…

Please send it to me offline… thanks.

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