A surface finish can be either organic or metallic in nature. Comparing both types and all available options can quickly demonstrate the relative benefits or drawbacks. Typically, the decisive factors when it comes to selecting the most suitable finish is the end application, the assembly process and the design of the PCB itself. Below you can find a brief summary of the most common finishes, however for further or more detailed information, please Viasion and we will be more than happy to answer any of your questions.
HASL - Tin/Lead hot air solder level Typical thickness 1 - 40um. Shelf life:12 months
Excellent solderability
Inexpensive / Low cost
Allows large processing window
Long industry experience / well known finish
Multiple thermal excursions
Difference in thickness / topography between large and small pads
Not suited for < 20mil pitch SMD & BGA
Bridging on fine pitch
Not ideal for HDI products
LF HASL – Lead Free hot air solder level Typical thickness 1 - 40um. Shelf life: 12 months
Excellent solderability
Relatively inexpensive
Allows large processing window
Multiple thermal excursions
Difference in thickness / topography between large and small pads - but to a lesser degree than SnPb
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