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Products > Packages > Semiconductor Device Mount Manual > PRINTED WIRING BOARD DESIGN > THDs >

CHAPTER 2 PRINTED WIRING BOARD DESIGN


2.3 THDs
2.3.1 Tolerance of package dimensions

The tolerance described in the package drawing of an 8 pin plastic DIP (7.62 mm (300)) is explained below.




 

Figure 2-15. Package Drawing of 8-Pin Plastic DIP (7.62mm(300))


The precision of the package pins in this diagram is guaranteed from the positional tolerance indicated by the logically accurate dimensions (dimension of square circumference: pin row interval/pitch), pin width/thickness tolerance, and pin position variation range.

[ Logically accurate dimensions ]


[ Pin width/thickness tolerance ]


[ positional tolerance: indicating the range of shift of the pin center position ]

Table 2-15. Description of Geometrical Tolerance
Symbol(211B) Symbol indicating the positional tolerance.
0.25 symbol(425B) Numerical value indicating that the positional tolerance of the pin center is in the range of x = 0.25 mm.
Allowable range that each pin center can deviate from the logically accurate dimensions when parallel chucking is performed at a pin row interval of e1 symbol(360B) = 7.62 mm for both pin rows of the DIP package.
Symbol indicating that the positional tolerance can be up to x = 25 mm, based on a pin width of b MAX = 0.60 mm.(i.e. If the pin width b is less than the maximum value, the tolerance will be greater than x = 0.25 mm)

To 2.2.2 Exrmple of mount pad dimensionTo 2.3.2 Pin existence range calculation