Circuit Board Repair Guide > Soldering > 7.3.2 Hot Gas Soldering of Surface Mount Chip Components

Hot Gas Soldering of Surface Mount Chip Components

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This procedure covers the general guidelines for hot gas soldering of 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.
 
Surface mount chip component soldered onto circuit board
Surface Mount Chip Component

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.

IPC Acceptability References
IPC-A-610 12.0 Surface Mount Assemblies
 
Related Procedure References
CTC 1.0 Foreword - Circuit Board Repair Guide
CTC 2.1 Handling Electronic Assemblies
CTC 2.2.1 How to Clean a Circuit Board
CTC 2.2.2 Cleaning Circuit Boards, Aqueous Batch Process
CTC 2.5 Baking and Preheating of Printed Circuit Boards
CTC 7.1.1 Quality Soldering Basics
CTC 7.1.2 Preparing Circuit Boards and Soldering Tools for Soldering and Component Removal
CTC 7.1.3 Solder Joint Acceptability Criteria for Various Component Types
IPC7711 5.3.1 Solder Paste Method

Tools and Materials
Cleaner
Flux
Hot Air Tool with Tips      
Microscope
Solder
Wipes

7.3.2 Soldering Surface Mount Chip Components, Hot Gas Method

Printed Board Type: R/F/C  |  Skill Level: Intermediate  |  Conformance Level: High  |  Rev.: C  |  Rev. Date: Jul 7, 2000

Add solder paste to each pad

Figure 1: Add a small bead of solder paste to each pad.


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.
 
Heat solder joints until solder melt observed

Figure 2: Move the tool back and
forth to heat both solder joints until complete solder melt is observed.


Chip capacitors generally have solid color bodies

Chip Capacitors generally have solid color bodies.



Capacitors A - Stripe

A - Stripe
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.




Links to Related Products


Prototyping Boards for Through Hole and SMT Components  
Prototyping Boards for Through Hole and SMT Components
These Schmartboard prototyping boards support through hole and surface mount components. This is the fastest and easiest electronic circuit prototyping system ever conceived.

The SchmartBoard|ez products are for people who may not have advanced soldering skills, first-timers, or just anyone who wants to have a fast, easy, and hassle-free experience.



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