First-Aid Kits for Circuit Boards
|
|
|
|
6.3 Component Modifications and Additions
Outline
This procedure covers the general guidelines for modifications that involve adding components.
Minimum Skill Level - Advanced
Recommended for technicians with soldering and component rework skills and exposure to most repair/rework procedures, but lacking extensive experience.
| Tools and Materials |
|
Cleaner
General purpose cleaner for removing contamination. |
|
Microscope
It is a challenge to undertake precision repair without a good microscope. |
|
Soldering Iron, Solder and Flux
A well maintained soldering iron is a must at every tech bench. |
|
Wipes
Nonabrasive, low-linting wipes for cleanup. |
|
General Rules
- 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.
- Leads of added components should not be inserted into plated holes occupied by another component lead.
- Added components placed on the circuit board surface should be placed on the component side of the assembly or circuit board unless otherwise specified.
- Added components shall not be raised above the board surface beyond allowable dimensions.
- Added components shall not cover over pads or vias used as test points.
- Added components shall not cover other component foot prints unless the layout of the assembly prohibits mounting in other areas.
- Added component leads may require insulation to avoid contact with component body or other conductors.
- Removal of existing solder from a connection point may be necessary to avoid bridging, or excess solder, in the final connection.
- Consider design limitations and product use environments when stacking components.
- Do not exceed minimum component lead bend radius.
- When possible, component identification marking shall be legible.
Procedure
- When required, form the component leads and clean the area.
- When required, secure the component in place by bending leads or other mechanical means.
- Apply flux to the joint.
- Place the soldering iron tip at the connection between both leads. Apply a small amount of solder at the connection of soldering iron tip and lead to form a solder bridge.
- Immediately feed solder into the joint from the side opposite from the soldering iron tip until the proper fillet is achieved. Remove the solder and iron simultaneously.
- When required, clean the flux residue.
- 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 axial component should not be inserted into the plated holes.
|
Figure 3: Axial lead component soldered to adjacent axial lead component. Note: Added component 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 added component 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 component body. |
This procedure is for reference only. Refer to the Procedure References listed above, or contact Circuit Technology Center for appropriate industry approved references.
|
|
CircuitMedic
22 Parkridge Road, Haverhill, MA 01835 USA
Phone: 978-373-1600 - Fax: 978-372-5700
Division of Circuit Technology Center, Inc.
Copyright © 2012 All rights reserved.
|
ISO9000:2008 Certified
|
|
Member Since 1986
|
|
|
|
|
|
|
