IEC 60749-30-2020 Semiconductor devices – Mechanical and climatic test methods – Part 30: Preconditioning of non-hermetic surface mount devices prior to reliability testing.
4 General description
Package cracking and electrical failure in plastic encapsulated SMDs can result when soldering heat raises the vapour pressure of moisture which has been absorbed into SMDs during storage. In this test method, such problems are assessed and SMDs are evaluated for heat resistance after being soaked in an environment which simulates moisture being absorbed while under storage in a warehouse or dry pack.
5 Test apparatus and materials
5.1 General
This test method requires, as a minimum, access to the following equipment.
5.2 Moisture chamber Moisture chamber(s) capable of operating at 85 °C/85 % RH (relative humidity), 85 °C/60 % RH, 85 °C/30 % RH, 30 °C/70 % RH and 30 °C/60 % RH. Within the chamber working area, temperature tolerance shall be ±2 °C and the RH tolerance shall be ±3 % RH. A chamber with 60 °C/60 % RH capability is optional for accelerated soak conditions.
5.3 Solder equipment Solder equipment shall consist of the following.
a) 1 00 % convection reflow system capable of maintaining the reflow profiles required by this document. This is the preferred equipment for solder reflow.
b) VPR (vapour phase reflow) chamber capable of operating the temperature profiles in IEC 60749-20 with appropriate fluids. The chamber shall be capable of heating the packages without collapsing the vapour blanket and of re-condensing the vapour to minimize loss of the vapour phase soldering liquid. The vapour phase soldering fluid shall vaporize at the appropriate temperature specified above.
c) Infrared (IR)/convection solder reflow equipment capable of maintaining the reflow profiles required by this document. It is recommended that this equipment use the IR to heat the air and not directly impinge upon the components under test.
d) Wave-solder equipment capable of maintaining the conditions in 6.4.4 of IEC 60749-20:2020.
NOTE The moisture sensitivity condition (classification) test results are dependent upon the package body temperature, rather than board or lead temperature. Convection and VPR are known to be more controllable and repeatable than IR. When there are correlation problems between VPR, IR/convection, convection and wave solder (if used), the convection results are considered as the standard.
5.4 Optical microscope Optical microscope (40X for external visual examination).
5.5 Electrical test equipment Electrical test equipment capable of performing room temperature DC and functional tests.
5.6 Drying (bake) oven Oven for drying (bake) capable of operating at 1 25 5 0 + °C.
5.7 Temperature cycle chamber (optional) A temperature cycle chamber capable of operating as a minimum over a range of −40 0 10 − °C to +60 0 10 + °C in accordance with IEC 60749-25. Acceptable alternative test conditions and temperature tolerances are found in Table 1 of IEC 60749-25:2003. This equipment is only required if 6.3 is used. 6 Procedure 6.1 General It is recommended that a prior evaluation be run according to the moisture sensitivity levels (MSLs) detailed in IEC 60749-20, using the appropriate method and similar devices, to determine which preconditioning sequence is suitable, i.e. likely to pass. Other moisture evaluation data can be consulted. However, the soak sequence in 6.5 needs to be consistent with the floor life information in Table 1 and Table 2.IEC 60749-30 pdf download.