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CHAPTER 3 SOLDERING CONDITIONS
| (a) Moisture absorption of package before soldering |
Figure 3-2-6 shows the influences of the moisture absorption of the package on the SMD before the device is soldered and mounted.
The threshold moisture absorption rate, beyond which the package is cracked, is 0.18% when the sample is stored at 85°C, 85%RH for 14 hours, and 0.125% when the sample is stored at 30°C, 70%RH for 192 hours. |
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| Figure 3-2-6. Relations Between Occurrence of Package Crack and Moisture Absorption Rate |
| < Moisture concentration characteristics >
Figure 3-2-7 shows a moisture concentration model in the package when a crack occurs. The moisture concentrations on the rear surface of the island (metal plate on which the chip is placed) coincide when the crack has occurred. |
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