Package Mounting Methods
Points requiring care for LGA (C-CSP/L-CSP) and BGA
1) Rules for printed circuit board design
Recommended rules for printed circuit board design applicable to LGA (Land Grid Array) (C-CSP: Ceramic Chip Size
Package; L-CSP: Leadframe CSP) and BGA (Ball Grid Array) are shown in Figure 10.
For land pitch of 1.0 mm
(Land diameter:
φ0.6
mm)
Land
φ0.5
mm
Resist hole diameter
φ0.6
mm
For land pitch of 0.8 mm
(Land diameter:
φ0.5
mm)
Land
φ0.4
mm
Resist hole diameter
φ0.5
mm
P
=
1.0 mm
P
=
0.8 mm
Figure 10 Printed circuit board design rules
2) Metal masks
The following specifications are recommended for metal masks. (Figure 11)
(a) Manufacturing method: Full additive
(b) Metal thickness A: 0.12 mm to 0.15 mm
(c) Opening diameter B:
φ0.6
mm to 1.0 mm pitch (CSP land diameter:
φ0.6
mm)
φ0.5
mm to 0.8 mm pitch (CSP land diameter:
φ0.5
mm)
B
A
Figure 11 Metal mask specifications
3) Cream solder
The following points should be considered when selecting the solder paste:
(a) Composition
There are no particular specifications. Currently, Sn-Pb eutectic compositions can be used without problems, but
since the use of Pb is becoming more restricted, sufficient consideration should be given to this point during
selection.
(b) Grain size
Printing characteristics are good for grain sizes of 20
µm
to 50
µm
(c) Viscosity
There are no particular specifications, but focus should be placed on characteristics such as sagging after printing,
the capability to print repeatedly, etc.
(d) Other
Be careful of the creation of solder balls after reflow.
M20
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