The surface finish of HASL and HASL(Lead Free)


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HASL and HASL(Lead free) is one of the major surface finish in PCB fabrication industry, and it’s a kind of cheap pcb manufacturing technology compared with other surface finishes. The process consist of emerging bare printed circuit board into tin lead alloy melting pot, and then use the “air knife” to blow hot air across the PCB board surface to remove excess solder.
Hot air solder leveling has an unexpected benefit that the process will make PCB exposure to the high temperature up to 265 ℃. This means that the process can well identify any potential delamiantion problem before assembling any expensive components to printed circuit board.

Basically the advantages and disadvantages for hot air solder leveling as below,

Advantages include:


• Low cost,
• Can be widely used
• Reworkable
• long shelf life


Disadvantages include:


• Uneven surface
• Not suitable for PCBS with fine pitch
• Contain Lead (HASL)
• Thermal shock
• Solder Bridge
• Plugged or Reduced plated through holes