Crown PSA-2 - Page 73

Problem: Rosin joint.
Characteristics: Joint is separated by a thin coat of flux producing high resistance to current.
Fig. 7.9 Rosin Joint
Cause: Solder applied previous to terminal reaching
minimum temperature (solder melting point).
When soldering individual component parts to printed
circuit boards, several procedures may be followed. The
following procedure complies to U.S. Government
standards and may be altered to suit a specific situtation.
1. Components leads should be bent to exact spacing of
mounting holes in PC board (Fig. 7.10). This allows leads
to enter PC board at right angles and relieves stress.
Fig. 7.10 Component Lead Spacing
2. Leads should be bent down tight to pad.
3. Leads should be bent in the direction of the run
connected to the pad and clipped at a_ length
approximately '4” (Fig. 7.11).
Fig. 7.11 Component Lead Bending
7-6
Remedy: Apply correct amount of heat; remove only
after good wetting and fillet is achieved.
4. Components should be held tight to the PC board
while clinching leads on other side (Fig. 7.12) and
soldered accordingly. Fig, 7.13 shows acceptable solder
joints.
si
Fig. 7.13 Acceptable Solder Joints