Panasonic ASCT1F46E manual Standard dimensions for the Hole and Land diameter

14.PC board design

2.Hole and Land diameter

3.Expansion and shrinkage of copper-clad laminates

12

The Hole and Land diameter are made with the hole slightly larger than the lead wire so that the component may be inserted easily. Also, when soldering, the solder will build up in an eyelet condition, increasing the mounting strength. The standard dimensions for the Hole diameter and Land are shown in the table below.

Standard dimensions for the Hole and Land diameter

Unit: mm/ inch

Standard Hole		Tolerance	Land diameter
di	t
0.8/ .031			2.0 to 3.0/ .079 to .118
1.0/ .039		±0.1/ ±.039
1.2/ .047			3.5 to 4.5/ .138 to .177
1.6/ .063

Remarks

•The Hole diameter is made 0.2 to 0.5mm/ .008 to .020inch larger than the lead diameter. However, if the jet method (wave type, jet type) of soldering is used, solder may pass through to the component side. Therefore, it is more suitable to make the Hole diameter equal to the lead diameter +0.2mm.

•The Land diameter should be 2 to 3 times the Hole diameter.

•Do not put more than 1 lead in one hole.

Because copper-clad laminates have a longitudinal and lateral direction, the manner of punching fabrication and layout must be observed with care. Expansion and shrinkage in the longitudinal direction due to heat is 1/15 to 1/2 of that in the lateral, and accordingly, after the punching fabrication, the distortion in the longitudinal direction will be 1/15 to 1/2 of that in the lateral direction. The mechanical strength in the longitudinal direction is 10 to 15% greater than that in the lateral direction. Because of this difference between the longitudinal and lateral directions, when products having long configurations are to be fabricated, the lengthwise direction of the configuration should be made in the longitudinal direction, and PC boards having a connector section should be made with the connector along the longitudinal side.(The figure below)

Example: As shown in the drawing below, the 150mm (5.906 inch) direction is taken in the longitudinal direction.

Also, as shown in the drawing below, when the pattern has a connector section, the direction is taken as shown by the arrow in the longitudinal direction.