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
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.
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Surface Mount Chip Component
Chip Capacitors generally
have solid color bodies. |
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.
Tools and Materials
Cleaner
Flux
Microscope
Solder
Soldering Iron with Tips
Wipes
Procedure
Figure 1: Pre-fill one pad with solder.
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| 1.
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Add liquid flux to one pad. |
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| 2. |
Pre-fill one pad with solder. (See
Figure 1). |
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| 3. |
Clean the area. |
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| 4. |
Add liquid flux to both pads. |
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Figure 2: Place the soldering iron tip
at the junction between the pre-filled pad and component
lead.
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| 5.
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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.
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| 6. |
Place the soldering iron tip at the junction
between the pre-filled 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).
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Figure 3: Solder the other opposite
side of the component.
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| 7.
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Remove the tip. Wait a moment for the solder
to solidify before soldering the other side
of the component. (See Figure 3).
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| 8. |
Clean, if required and inspect. |
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