Some product failures are caused by moisture. It infiltrates into product along IC enclosure seals or gaps between pins which conducts metals within IC and results in short circuit or current leak. The Temperature and Humidity test is designed to test resistance of IC enclosures against moisture to assure product reliability.
Test conditions
Verify and assess resistance of packaging substance and internal circuits of non-sealed electronic components against moisture corrosion under accelerating factors of high temperature, humidity, and pressure. Test conditions for consumer electronics defined by JEDED may cover THB, HAST, uHAST, and PCT.
| Test Item | Temperature | Humidity | Vapor Pressure | Bias | Test Duration |
|---|---|---|---|---|---|
| HAST | 130±2 ℃ | 85±5% | 33.3psia | V cc max | 96(-0,+2)Hrs |
| 110±2 ℃ | 85±5% | 17.7psia | V cc max | 264(-0,+2)Hrs. | |
| THB | 85±2 ℃ | 85±5% | 7.12psia | V cc max | 1000(-24,+168)Hrs. |
| uHAST | 130±2 ℃ | 85±5% | 33.3psia | NA | 96(-0,+2)Hrs. |
| 110±2 ℃ | 85±5% | 17.7psia | NA | 264(-0,+2)Hrs. | |
| PCT | 121±2 ℃ | 100% | 29.7 psia | NA | 96(-0, +5) Hrs duration is typical for this test. |
* You may execute either HAST or THB as the former is accelerating version of the latter
* uHAST assessment is not needed after the execution of HAST or THB, according to JESD47
Failure model
Place DUT in test environment of high temperature, humidity, and pressure then apply voltage to infiltrate moisture into product along interface with EMC, lead frame or substrate and to identify the following failures:
- Interface connectivity
- Change of metal compound between wire bonding material and wafer or aluminum pad
- Ion migration due to electrolytic corrosion which, in turn, lead to short-circuit leak, see figure below for illustration
Ion migration releases tree shaped metal which result in interconnection of metals in different area
The Superiority of iST
- Professional PCB preparation team capability of making HAST/THB test boards
Reference specification
- JESD 47/JESD 22-A101/JESD 22-A110/
JESD 22-A118/JESD 22-A102 - IEC 60068-2-66
- AEC-Q100/AEC-Q101/AEC-Q102
- Type：Reach-in chamber
- Applicability：HAST/uHAST/PCT
- Brand：Espec/Kson
- Type：Temperature (and humidity) chamber
- Applicability：THB/THT
- Brand：Espec/Kson
- Automotive/commercial/industrial/consumer electronics