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Products > Packages > Semiconductor Device Mount Manual > SOLDER JOINT RELIABILITY >

CHAPTER 5 SOLDER JOINT RELIABILITY


5.4 Single-sided Soldering and Double-sided Soldering

The results of performing single-side and double-side shifted mounting and then comparing the temperature cycle characteristics are shown below. These results show that type IV, under which the package mounted on the bottom side is shifted by an amount equal to its entire width, yields almost the same temperature cycle characteristics as single-side soldering.
When designing the printed wiring board, find ways not to place another package immediately under the target product.

Double-sided soldering evaluation

Type I Type II Type III Type IV
Type I
Mounted at same position



 Type II
Chip edge of bottom CSP aligned to center of top CSP

 Type III
Chip edge of bottom CSP aligned to chip edge of top CSP

 Type IV
Edge of balls of bottom CSP shifted 1 pitch outward from edge of balls of top CSP

Single-sided Soldering and Double-sided Soldering
Single-sided Soldering and Double-sided Soldering

<Test conditions>

  ♦ Package:
     • 7 x 7mm, 84 pin FPBGA,
     • 0.5mm pitch
     • Ball composition: Sn-37Pb
  ♦ Printed wiring board:
     • 6-layer buildup substrate
     • t1.4mm
  ♦ Solder paste:
     • Sn-37Pb
To 5.3 Influence of Pad Structure of Printed Wiring BoardTo 5.5 Combinations of Device Plating and Solder Material


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