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 metallized 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.  

ACCEPTABILITY REFERENCES
IPC-A-610	12.0	Surface Mount Assemblies
PROCEDURE REFERENCE
CTC 7721	1.0	Foreword
CTC 7721	2.1	Handling Electronic Assemblies
CTC 7721	2.2	Cleaning
CTC 7721	2.5	Baking and Preheating
CTC 7711	7.1.1	Soldering Basics
CTC 7711	7.1.2	Preparation For Soldering And Component Removal
CTC 7711	7.1.3	Solder Joint Acceptability Criteria
IPC 7711	5.3.1	Solder Paste Method

TOOLS & MATERIALS
Cleaner
Flux
Hot Air Tool with Tips
Microscope
Solder
Wipes

PROCEDURE

1. Add a small bead of solder paste to each pad. (See Figure 1).



2. Place the component in position.



3. Adjust the pressure and temperature output of the hot air tool.



4. Direct the hot air over the component with the hot air tool tip approximately 2.50 cm (1.00") from the solder joint. This initial heating will pre-dry the solder paste.

   NOTE
   When the solder paste has pre-dried, the paste will have a dull flat appearance




5. When the solder paste has dried, move the hot air tool tip to approximately 0.50 cm (0.20") above the component. Move the tool back and forth to heat both solder joints until complete solder melt is observed. (See Figure 2).



6. Remove the tool. Wait a moment for the solder to solidify.



7. Clean, if required and inspect.