Package Mounting Methods
Printed circuit board selection
The important point for surface mounting is to greatly minimize the stress due to this heat and warpage. In order to do so,
printed circuit board material which has the minimum possible dimension change ratio or warpage due to external stress is
desirable. Figure 6.2 shows comparison data for glass epoxy material and paper phenol material commonly used in
consumer products.
Although it would be ideal to use 1.6 mm-thick glass epoxy material, its high cost cannot be avoided, and actually paper
phenol material is widely used. In this case, consideration must be given to greatly minimizing the heat stress and reducing
printed circuit board warpage during the mounting processes.
Relationship between heating temperature and dimensional change
Dimensional change ratio (%)
Paper phenol
3.0
2.0
Glass epoxy
1.0
30
50
70
90
110 130 150 170
Heating temperature (°C)
Relationship between external stress and warpage
Paper
material/phenol
resin; t = 1.0 mm
Force Warpage
90 mm
5
4
3
2
1
0
10
20
30
Glass
material/epoxy
resin; t = 1.6 mm
40
50
Paper
material/phenol
resin; t = 1.6 mm
7
Warpage (mm)
6
Glass
material/epoxy
resin; t = 1.15 mm
External stress (N)
M
Figure 2 Dimensional change ratio and warpage for printed circuit board materials
M9
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