The following is a guide to help you fill out our quad pack and flat pack spec sheets. Please furnish the parameters listed below and call us if you need further information or technical assistance.
A. Stand-Off/PCB Offset Height - This dimension can vary and may sometimes include clearance for a heat sink. On the forming tool, this dimension is adjustable with a micrometer. Usual tolerance is ± .002.
B. Shoulder - This is only noted on our Universal spec sheets. It is the distance from the body of the device to thevertical tangent of the first bend, "G." This dimension is critical and size range depends on body type and lead thickness. For instance, the "B" dimension for ceramic parts can be as small as .030" and for plastic parts could be as low as .010". Metal Glass Seal parts will require a substantially larger "B" dimension. A suitable should dimension is often a judgement call based on therequired footprint vs. part size and type.
C. Lead Material Thickness - This is the total thickness including plating (and tinning, if applicable). This is a very critical dimension and enormously effects spring-back, foot position, burnish (on the leg) and your tip-to-tip "D" tolerance. The smaller range the better. Usual tolerance here is ± .002" (ideal is .001"±).
D. Tip-to-Tip - This is the required size of the device after form and trim. This dimension includes spring back and cumulative tolerance. Usual tolerance here is ± .010".
E. Foot Option #1 - This is the total foot length that will encounter solder, measured from the tip to the virtical tangent. Tolerance here is ± .005". This dimension typically ranges from .030" to .060".
Foot Option #2 - This represents the JEDEC method of specifying this dimension. As is the case with Foot Option #1, tolerance is normally ± .005" and size range typically varies from .025" to .060".
F. Overall Body Thickness - This dimension should include covers and/or heat sinks. Significant variations in this dimension within part lots can cause unacceptable variations in the final "D" dimension. Please use or send us the manufacturers case drawing to eliminate confusion.
G. /H. Upper & Lower Radii - These, as a rule, should be 1 ½ to 2 x the maximum material thickness "C". A typical tolerance range for these values is +/004-.002 or slightly greater depending on the lead thickness tolerance. Please contact us if you have any questions.