|4.3.1 Circuit Cut, Surface Circuits
This method is used to sever a circuit or short. A small section of the circuit is removed forming a break. The width of the break should be at least as wide as the minimum conductor spacing. The Surgical Knife or high speed, Micro-Drill System is used. This method is recommended for surface circuit cuts only. After cutting, the area is sealed with epoxy.
This method is recommended for surface circuit cuts only.
Minimum Skill Level - Advanced
Recommended for technicians with soldering and component rework skills and exposure to most repair/rework procedures, but lacking extensive experience.
Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.
||Externally Observable Characteristics
Images and Figures
|Tools and Materials|
General purpose cleaner for removing contamination.
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
Meter and probes to test for electrical continuity.
It is a challenge to undertake precision repair without a good microscope.
||Micro Drill System
Versatile power tool for milling, drilling, grinding, cutting and sanding circuit boards.
General purpose oven for drying, baking and curing epoxies.
Nonabrasive, low-linting wipes for cleanup.
|Circuit Cut, Surface Circuit|
|Figure 1: Option A - Make two small cuts with the knife and remove a short section of circuit.|
|Figure 2: A high quality, Micro-Drill System is recommended for this delicate operation.|
|Figure 3: Make 1 or 2 cuts as needed to cut circuit.|
|Figure 4: Completed repair.|
- Identify the circuit
or short to be cut. Determine from the artwork or drawings where the
best location is to make the break. The width of the break should at
least match the minimum required electrical
- Clean the
- Carefully make two small
cuts with the knife and remove the short section of circuit. (See Figure
1) Or use a Micro-Drill as covered in the next
- Select the appropriate
size ball mill and insert it into the Micro-Drill System. Set the speed
to high. (See Figure 2) The ball mill should be approximately the same
width as the circuit to be cut.
Ball mills should be
dental grade carbide steel for precision cutting and long
- Carefully make 1 or 2 cuts
as needed. (See Figure 3)
Exercise care to avoid damage to
continuity to be sure that the circuit has been
- Clean the area.
- Mix epoxy. If desired, add
color agent to the mixed epoxy to match the circuit board
- Coat the area with epoxy
if needed. An epoxy dispenser may be used to control the application of
epoxy. Remove any excess.
the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
examination of cuts for spacing, and unintended damage to surrounding
- Electrical tests as
Procedure for reference only.