Why do more assemblers use halogen-free printed boards

- Feb 21, 2019-

Brominated flame retardants have long been used in the manufacture of printed circuit boards, and although some halogen-free alternatives have been developed by suppliers, their impact on the assembly process remains highly uncertain.Since the implementation of halogen free, although halogen free materials have occupied 10% of the laminate market share, the industry still lacks experience in defining assembly processes and manufacturing reliability Windows.

The price of halogen-free PCB is higher than that of common halogen-free PCB.The cost difference is purely economic, however, and SMT SMT manufacturers are facing a more critical challenge: PCB drilling is heavily influenced by the physical properties of the material, while halogen-free materials are generally harder and are estimated to reduce the life of the bit by about 25%.This is by no means insignificant, for this reason it is possible that halogen-free PCBS will cost more to manufacture.When sold to an assembly plant, this cost will be reflected in the selling price of the product.

The good news is that the halogen-free circuit boards that the assemblers are focusing on are even better than the halogen-free ones.From some of the data table is provided by the supplier, you can easily see, halogen-free, substrate usually have low coefficient of thermal expansion (CTE), they have longer time T - 260, T - 288 and a higher temperature of the Td, it means no halogen PCB will be better able to apply to many times reflow process, and able to withstand higher reflow temperature.

From a reliability perspective, a significant number of defects are related to CAF.CAF (anode conductive wire) is an electrochemical failure mode caused by the growth of thin wire between the inner layers of PCB.This is usually because certain types of inner layers are layered, creating a space that allows the filaments to grow, and this layering is due to a mismatch between the thermal expansion coefficients of the epoxy and the fiberglass.Some studies in South Asia have shown that halogen-free plates are more resistant to CAF formation, while another study by CALCE has shown that halogen-free plates are more likely to form CAF.For any company that assembles products with high reliability requirements, the data on this mutual shield should be of great concern.As more independent work continues, it will become clearer whether CAF is a critical factor.

The above is the industry information provided by FASTPCBA. Hope it can be helpful to you!


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