PWB Hole


	
			     TABLE 1
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	    THE FOLLOWING GENERAL DESIGN GUIDE LINES MAY BE
    USED TO DETERMINE COMPONENT SPACING, HOLE SIZES, AND PAD SIZES
                      FOR PWB COMPONENTS
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HOLE SIZES = maximum lead size + .015 tolerance, then select next 
	     larger drill size.
ANNULAR RING = the ring of copper left after drilling the hole, 
	       min is .030.
PAD SIZE = maximum hole size + min annular ring (.030)

COMPONENT SPACING = maximum body length + 6 x the lead diameter, then 
	   	    slect next higher grid spacing.
  
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			     TABLE 2
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  STANDARD TERMINAL AREAS/HOLE SIZES FOR PRINTED WIRING BOARDS
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    TERMINAL    HOLE     DRILL  NOM LEAD    MAX LEAD
      AREA      SIZE     SIZE    DIA  1)     DIA 2)
      .055   .018-.025   .020  
      .062   .023-.033   .028   UP TO .018   .022
   4) .062   .026-.036   .031   .019-.021    .025
   5) .068   .026-.036   .031   .019-.021    .025
      .078   .031-.041   .036   .022-.026    .030
      .093   .040-.050   .045   .027-.035    .039
      .100   .050-.060   .055   .036-.045    .049
      .110   .055-.065   .060   .046-.050    .054
      .125   .062-.072   .067   .051-.057    .061
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1) MIL-STD-275 CALLS FOR .010 TO .028 NOM CLR, LEAD TO HOLE. IN THE
   CASE OF FLAT RIBBON LEADS, THE DIFFERENCE BETWEEN THE LEAD 
   THICKNESS AND THE HOLE SHALL NOT EXCEED .028 NOMINALLY.

2) MINIMUM TERMINAL AREA = MAXIMUM HOLE + .034, PER MIL-STD-275.

4) SHOULD BE USED ON 2 SIDED BOARDS ONLY.
	
5) .068 TERMINAL WITH .031 HOLE IS PREFERRED.

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