7.3.1 Soldering Surface Mount Chip Components, Point To Point Method
Outline
This procedure covers the general guidelines for soldering surface mount chip components. The following surface mount chip components are covered by this procedure. While all of these components are different, the techniques for soldering are relatively similar
Chip Resistors: The component body of chip resistors is made out of alumna; an extremely hard, white-colored material. The resistive material is normally located on the top. Chip resistors are usually mounted with the resistive element facing upwards to help dissipate heat.
Ceramic Capacitors: These components are constructed from several layers of ceramic with internal metalized layers. Because metal heats up much faster than ceramic, ceramic capacitors need to be heated slowly to avoid internal separations between the ceramic and the metal layers. Internal damage will not generally be visible since any cracks will be inside the ceramic body of the component.
Note: Avoid rapid heating of ceramic chip capacitors during soldering operations.
Plastic Body: Another style of chip component has a molded plastic body that protects the internal circuitry. There are a number of different types of components that share this type of exterior package. The termination styles for plastic chip component packages vary considerably.
MELF: MELF - Metal Electrode Face cylindrical components. These may be capacitors, resistors, and diodes. It can be hard to tell them apart - since there is no universal coloring or component designators printed on the component bodies.
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.
Cleaner
General purpose cleaner for removing contamination.
Microscope
Precision microscope with stand and lighting for work and inspection.
Soldering Iron
Properly maintained soldering iron and properly sized soldering iron tips.
Wipes
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
Surface Mount Chip Component
Figure 1: Prefill one pad with solder.
Figure 2: Place the soldering iron tip at the junction between the prefilled pad and component lead.
Figure 3: Solder the other opposite side of the component.
Chip Capacitors generally have solid color bodies.
Procedure
Add liquid flux to one pad.
Prefill one pad with solder. (See Figure 1)
Clean the area.
Add liquid flux to both pads.
Place the component in position and hold it steady with a wooden stick or tweezers so that the soldering iron won't push the component out of alignment.
Place the soldering iron tip at the junction between the prefilled pad and component lead. Flow the solder until the component drops down and is soldered in position. Apply additional solder as needed. (See Figure 2)
Remove the tip. Wait a moment for the solder to solidify before soldering the other side of the component. (See Figure 3)
