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Printed Board Type: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: F
Revision Date: Mar 28, 2001

OUTLINE

This procedure covers baking and preheating of printed boards and printed board assemblies to prepare the product for the subsequent operations. Included are steps for:  

1. Baking
   Baking is used to eliminate absorbed moisture. Whenever possible circuit boards and circuit Board assemblies should be baked prior to soldering, unsoldering and coating operation to prevent blistering, measling or other laminate degradation.
   
   
2. Preheating
   Preheating is used to promote the adhesion of subsequent materials to the board surfaces and to raise the temperature of the circuit board to allow soldering and unsoldering operations to be completed more quickly.
   
   
3. Auxiliary Heating
   Auxiliary heating is the addition of a second source of heat. This can be from a hot air tool, or from a second soldering station. A common application is to provide additional heat when removing through hole components that may have connections to internal power or ground planes.
   
   
4. Thermal Profiles
   Ball Grid Array, Chip Scale Packages, and Flip Chip Packages may require the development of "Time Temperature Profiles" to remove or install these devices.

CAUTION
Baking and preheating procedures must be carefully selected to ensure that temperature and time cycles used do not degrade the product. Environmental conditions must also be carefully considered to ensure that vapors, gases, etc., generated during the heating process do not contaminate the product's surfaces.

CAUTION
Some manufacturers of ceramic chip capacitors recommend that the Preheat Ramp Rate not exceed 2-4 癈/Sec.

CAUTION
To prevent fluxes or other contaminates from being baked onto the board surface, thoroughly clean the board or assembly prior to baking or preheating.

TOOLS & MATERIALS
Cleaner
Oven
Wipes

Printed Board Type: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: D
Revision Date: Jul 1, 1997

OUTLINE
This method can be used to add, change or replace legend and markings on printed boards or printed board assemblies. This method uses epoxy ink and an ink stamp to place the legends on the printed board surface in much the same manner as taking a "finger print".

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Damaged Legend

PROCEDURE

1. Figure 1: Apply legend using a peg stamp.

   Clean the area.
   
   
2. Scrape off any remaining character or legend with a knife and clean the area.
   
   CAUTION
   Abrasion operations can generate electrostatic charges.
   
   
3. Select the appropriate characters from the peg stamp set or have a special stamp made up.
   
   
4. Mix the epoxy ink. White is the most common color. Spread a thin even coating of the epoxy ink on the ink plate or on a smooth surface.
   
   
5. Gently press the peg stamp into the epoxy coating to coat the character surface.
   
   

6. Figure 2: Completed legend repair.

   Gently press the peg stamp onto the desired location on the circuit board surface. (See Figure 1).
   
   
7. Cure the epoxy ink per the manufacturer's instructions.

EVALUATION

1. Visual examination for proper characters, positioning and legibility.