In mid 2009, International Patent Classification (IPC) announced a new verification method 2.6.27 “Thermal Stress, Convection Reflow Assembly Simulation”, which appeared to replace the traditional one - Thermal stress T288. This has been a good news to end users of system, but an extended mishap to PCB suppliers, meaning their products are to face more harsh challenges.
Before the lead free issue in PCBA applications can be fully overcome, international organizations actively begin to promote application development of halogen free PCBs to cope with environmental requirements. This is a further mishap to the PCB industry. PCB attributes enabled evasion of total halogen control issues in the last transfer of RoHS; however the current appeal for halogen free has created more obvious impacts to the industry.
For necessary changes of material properties that cope with the transfer, main problems in halogen free PCBs include hardening and crisping effects, reduced bonding force of copper foil that leads to reduced pad bond strength, pool quality of drill holes due to material hardening, and an increase of wick effects. These problems lead to reduced time of Conductive Anode Filament (CAF), high-frequency instability and Pad Cratering, therefore the design of verification has to make different considerations than the traditional ones, test vehicles must be designed to facilitate product verification. For overcoming Pad Cratering and the Pad bonding strength issue, SMD design overrides NSMD design, which is a totally different approach from the conventional PCB design. Also, PTH pitch and arrangement are key considerations for slowing down the happening of Conductive Anodic Filaments (CAF).
PCB Reliability Verification
Thermal Stress Test
Reflow Simulation Test
Temperature Humidity Bias Test
Hot Oil Test
PCB Insulation Resistance Test
Insulation Resistance Measurement
Contact Resistance Measurement
Dielectric Withstanding Voltage Test
Ion Contamination Measurement
Glass Transition Temp.Measurement(Tg)
Thermal Shock Test
Surface Insulation Resistance Test(SIR Test)
Conductive Anodic Filaments Test(CAF Test）
Creep Corrosin Test
We have developed verification methods for halogen free PCBs, including design of test vehicles, which may be of help to the customer in carrying out preliminary verification of product durability or sampling analysis, assisting the customer to enter into mass production smoothly.
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