IPC 7711A - 第54页
NOTES IPC-771 1A/7721A Number: 2.5 Revision: Date: 2/98 Subject: Baking and Preheating P a g e2o f2 Copyright Association Connecting Electronics Industries Provided by IHS under license with IPC Not for Resale No reprodu…
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:
A. Baking
Baking is used to eliminate absorbed moisture. Whenever possible printed wir-
ing boards and printed wiring board assemblies should be baked prior to solder-
ing, unsoldering and coating operation to prevent blistering, measling or other
laminate degradation.
B. Preheating
Preheating is used to promote the adhesion of subsequent materials to the
board surfaces and to raise the temperature of the printed wiring board to allow
soldering and unsoldering operations to be completed more quickly.
CAUTION
Baking and preheating procedures must be carefully selected to ensure that tem-
perature and time cycles used do not degrade the product. Environmental conditions
must also be carefully considered to ensure that vapors, gases, etc., generated dur-
ing the heating process do not contaminate the product’s surfaces.
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.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
TOOLS & MATERIALS
Cleaner
Cleaning Wipes
Oven
EVALUATION
7711A/7721A
General
Information and
Common Procedures
Revision:
Date: 2/98
Baking and Preheating
Number: 2.5
Product Class: R, F, W, C
Skill Level: Intermediate
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
NOTES
IPC-7711A/7721A
Number: 2.5
Revision:
Date: 2/98
Subject: Baking and Preheating
Page2of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
OUTLINE
This procedure covers epoxy mixing and handling. The epoxy covered by this pro-
cedure has multiple uses including solder resist repair, base board repair, circuitry
over-coating and delamination repair.
NOTE
For high strength or high temperature applications two part epoxies will generally
have the best properties.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
TOOLS AND MATERIALS
Balance/Scale
Cleaner
Color Agent, Various Colors
Epoxy
Foam Swab
Heat Lamp
Mixing Cup
Mixing Stick
Oven
Wipes
PRINTED WIRING BOARD PREPARATION
The area where the epoxy is to be applied should be prepared prior to mixing the
epoxy. This preparation may include preheating the affected area to improve absorp-
tion of the applied epoxy. The entire printed wiring board may also be heated in an
oven or with a heat lamp.
CAUTION
Some components may be sensitive to high temperatures.
CAUTION
Avoid skin contact with epoxy materials.
PROCEDURE - Prepackaged Two Part Epoxy
1. Remove the clip separating the resin and activator. Mix by squeezing both halves
together with your fingers. Mix for at least one minute to ensure a complete mix
of the resin and activator. (See Figure 1.)
2. Cut open one end of the epoxy tube and squeeze the contents into a mixing cup.
Mix again with a mixing stick to ensure a thorough mixture of the resin and acti-
vator.
Figure 1 Mix resin and activator
inside package of prepackaged epoxy.
Figure 2 Apply epoxy. Foam swab
may be used to add texture.
7711A/7721A
General
Information and
Common Procedures
Revision:
Date: 2/98
Epoxy Mixing
and Handling
Number: 2.6
Product Class: R, F, W, C
Skill Level: Intermediate
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---