Circuit Board Repair Guide > Basic Circuit Board Repair Procedures > 2.5 Baking and Preheating of Printed Circuit Boards

Baking and Preheating of Printed Circuit Boards

Repair Circuit Boards | Repair SMT Pads | Repair BGA Pads | Repair Lands | Repair Edge Contacts
Repair a Conductor | Plated Hole Repair | Base Board Repair | Replace Solder Mask or Coatings

This section covers baking and preheating of printed circuit boards and printed circuit board assemblies to prepare the product for subsequent operations. Included are steps for baking, preheating, auxiliary heating, and thermal profiles.
  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 °C/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.

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
IPC 7721 2.5 Baking and Preheating
 
Tools and Materials
Cleaner
Oven
Wipes




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