At 10:16 PM 4/8/96, Kitty Hines wrote:
>I am looking for information on the spacing requirements necessary 
>to meet UL approval.  Can anyone give me a reference on where to 
>find these specs?
>
>I'm also looking for information on the spacing requirements 
>necessary for auto-insertion.  I know resistors have to be spaced 
>120-125 mils apart and radial caps cannot be auto-inserted.  What 
>about IC's and other parts?  Are the spacings different for 
>different pick-and-place machines?  What guidelines do you go by?
>
>Thanx for your help.
>
Kitty;

As far a UL approvals: The primary and secondary voltages should not be on
the same card. What is important, is whether the board is accessible while
under power or not. If it is accessible, then UL wants to see the product,
not just the board. If it is not accessible, then they are not as
interested. The board manufacturer must certifiy his construction method and
materials to UL-796. He has a yellow card expalining what he is certified
to.You will not find anything written down for product safety requirements
for UL, VDE,etc. They are very vague and prefer to look at finished product.

As far as assembly pick and place requirements, the most important thing is
to clear the insertion heads. The IPC-CM-770, Component Mounting Guideslines
for Printed Boards presents a good tutorial about mounting techniques and
auto-insertion.


Regards,

Gary Ferrari
Tech Circuits
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