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高频印制电路板上阻焊剂的困惑若在PCB的外层有射频线路,阻焊层覆盖于射频传输线就会影响阻抗。这是因为通常阻焊剂的介质损耗和吸湿性远大于高频层压板,导致插入损耗更大。而阻焊层厚度越大产生的损耗也越大。设计师要考虑到这个问题,可以在PCB外层高频电路上不覆盖阻焊剂,为保护线路采用ENIG涂层保护,然而镍层同样会带来高频损耗,需要设计师权衡考虑。
High-frequency PCB solder mask confusion If there is RF circuit in the outer PCB, solder mask covering the RF transmission line will affect the impedance. This is because typically the solder loss and moisture absorption is much greater than high frequency laminates, leading to greater insertion loss. The greater the thickness of solder mask the greater the loss. Designers should consider this issue, can not cover the PCB outer high-frequency circuit solder mask for the protection of the circuit with ENIG coating protection, but the nickel layer will also bring high-frequency loss, the designer weigh the consideration.