6.3 Component Modifications and Additions

Outline

This procedure covers the general guidelines for modifications that involve adding components.

Minimum Skill Level - Advanced

Tools and Materials

Cleaner General purpose cleaner for removing contamination.

Flex-Rack PCB Holder Sturdy rack for PCBs used for rework and positioning.

Microscope Precision microscope with stand and lighting for work and inspection.

Precision Tool Set Nine precision-crafted tools for detailed circuit board work.

Soldering Iron Properly maintained soldering iron and properly sized soldering iron tips.

Wipes Nonabrasive, low-linting wipes for cleanup.

Procedure

General Rules

1. Added components may need to be secured with adhesive or by other means if the component leads or component body would be subjected to mechanical stress.
2. Leads of added components should not be inserted into plated holes occupied by another component lead.
3. Added components placed on the circuit board surface should be placed on the component side of the assembly or circuit board unless otherwise specified.
4. Added components shall not be raised above the board surface beyond allowable dimensions.
5. Added components shall not cover over pads or vias used as test points.
6. Added components shall not cover other component footprints unless the layout of the assembly prohibits mounting in other areas.
7. Added component leads may require insulation to avoid contact with the component body or other conductors.
8. Removal of existing solder from a connection point may be necessary to avoid bridging, or excess solder, in the final connection.
9. Consider design limitations and product use environments when stacking components.
10. Do not exceed minimum component lead bend radius.
11. When possible, component identification marking shall be legible.

Procedure

1. When required, form the component leads and clean the area.
2. When required, secure the component in place by bending leads or other mechanical means.
3. Apply flux to the joint.
4. Place the soldering iron tip at the connection between both leads. Apply a small amount of solder at the connection of the soldering iron tip and lead to form a solder bridge.
5. Immediately feed the solder into the joint from the side opposite of the soldering iron tip until the proper fillet is achieved. Remove the solder and iron simultaneously.
6. When required, clean the flux residue.
7. Inspect

Component Modifications and Additions Figures

Figure 1: Radial lead component soldered to through-hole component leads. Note: Leads of the radial component should not need to be inserted into the plated holes.

Figure 2: Axial lead component soldered to through-hole component leads. Note: Leads of the axial component should not be inserted into the plated holes.

Figure 3: Axial lead component soldered to the adjacent axial lead component. Note: Added components may be stacked vertically or horizontally.

Figure 4: Chip component soldered to surface mount component using jumper wires. Note: One lead of surface mount component is shown lifted.

Figure 5: DIP component stacked and soldered onto another DIP component. One lead shown clipped. Note: Leads of the added components should not be inserted into the plated holes.

Figure 6: Chip cap bridging adjacent leads.

Figure 7: Chip component bridging leads of surface mount component.

Figure 8: Chip component stacked onto another chip component.

Figure 9: Surface mount component mounted upside down with jumper wires attached. Note: One lead is bent outward.

Figure 10: DIP Component mounted upside down with jumper wires attached.

Figure 11: Chip component mounted to one pad only.

Figure 12: Radial lead component mounted upside down. Note: Insulate leads to avoid contact with the component body.

Images

Component Modifications and Additions

See the procedure below for detailed instructions.