7.3.1 Soldering Surface Mount Chip Components, Point To Point Method

Printed Board Type: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: D
Revision Date: Jul 7, 2000

OUTLINE

Surface Mount Chip Component

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.

Figure 1: Prefill one pad with solder.

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.

Figure 2: Place the soldering iron tip at the junction between the prefilled pad and component lead.

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
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.5	Baking and Preheating
7.1.1	Soldering Basics
7.1.2	Preparation For Soldering And Component Removal
7.1.3	Solder Joint Acceptability Criteria
IPC7711 5.3.1	Solder Paste Method

Figure 3: Solder the other opposite side of the component.

TOOLS & MATERIALS
Cleaner
Flux
Microscope
Solder
Soldering Iron with Tips
Wipes

PROCEDURE

1. Add liquid flux to one pad.
   
   
2. Prefill one pad with solder. (See Figure 1).
   
   

3. Chip Capacitors generally have solid color bodies.

   Clean the area.
   
   
4. Add liquid flux to both pads.
   
   
5. 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.
   
   
6. 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).
   
   
7. Remove the tip. Wait a moment for the solder to solidify before soldering the other side of the component. (See Figure 3).
   
   
8. Clean, if required and inspect.