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22 Parkridge Road Haverhill, MA 01835 USA www.circuitrework.com |
This procedure covers one commonly used method for removing surface mount chip components.
Note: The goal when removing any component is to remove the component as quickly as possible.
Caution - Glued Components: A small dot of epoxy is often used to hold chip components in position during wave soldering processing. Typically these components will be located on the bottom side of a circuit board that has through-hole components located on the other side. Whenever you see a board like this, you can generally assume that the chip components will be glued onto the board. You'll need to leave the tip on the component for one or two additional seconds in order to transfer enough heat to over-cure or soften the adhesive. If required, take a wooden stick or curved tweezers and push the component sideways until the glue joint finally gives way.
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Minimum Skill Level - Intermediate Recommended for technicians with skills in basic soldering and component rework, but may be inexperienced in general repair/rework procedures. 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. |
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Tip Preparation
Forked tips are designed to fit over the top of chip components and to reflow both solder joints at once. The ends of the forked tip fit over the component with just a slight amount of extra space for solder. Measure the overall length and width of the component with a caliper to select the proper size tip. Check the tip for proper fit prior to processing the part.
The tip should not fit the component so tightly that it will get lodged in the tip, but the tip should not be so loose that it will not conduct heat to the leads simultaneously. The size and shape of the forked tip will have an effect on the rate of heat transfer. Larger tips with more surface area will transfer heat faster than smaller tips.
Forked tips can be used to remove a number of different styles of chip components, but the component must fit properly in the tool cavity. Since forked tips have a cavity, they require special cleaning and tinning procedures.
The solder provides surface tension to lift the component off the pads after reflow. Since the tip has more metal surface area than the pads on the circuit board, the solder will be drawn toward the metal tip, and so will the component.
Note: Determine the direction the part is to be swept off the circuit board surface. Densely packed circuit board assemblies often leave only one direction for the rework tool to follow when sweeping the part off the surface.
SOT Component Removal
