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Products > Packages > Semiconductor Device Mount Manual > SOLDERING CONDITIONS >

CHAPTER 3 SOLDERING CONDITIONS


3.2 Heat Resistance
3.2.1 Mechanism of Package Crack

A plastic package absorbs moisture even when it is stored at room temperature.
If the package is subjected to heat stress of soldering, the reliability of the device may be degraded, or delamination or cracks may occur inside the package.
Typically a package crack occurs at the point of stress where the adhesive strength is weakest.

新光CZ処理 ヘッダパターンの写真(10.4KB)

IR35-00-2条件の写真(8.76KB)

Photo 3-2-1. Package Crack


The mechanisms are shown in following.

(1) Moisture absorption of package

· Bulk absorption
· Surface absorption
   
(2) Soldering process

· Abrupt thermal stress
         
· Abrupt rise of package temperature
   
(3) Increase in internal force of package

· Vaporization and expansion of absorbed moisture
· Difference in thermal expansion of each material
   
(4) Occurrence of delamination
(to concentration of internal force)
   
(5) Occurrence of package crack
( to decrease in internal force)

Figure 3-2-1. Mechanism of Package Crack Occurrence
To 3.1.5(2) Lead material: CuTo 3.2.2 Package Moisture Absorption