IPC-4554-2005 浸没镀锡印刷电路板规范

IPC-4554
March 2005
Specification for
Immersion Tin Plating
for Printed Circuit Boards
5th DRAFT
Plating Subcommittee (4-14)

1.1 Scope
This specification sets the requirements for the use of Immersion Tin (ISn) as a surface finish for
printed circuit boards. This specification is intended to set requirements for ISn deposit thickness
based on performance criteria. It is intended for use by supplier, manufacturer, contract
manufacturer (CM) and original equipment manufacturer (OEM).
1.2 Description
ISn is a chemically deposited metallic finish that is applied directly over the basis metal of the PWB,
i.e copper. It is a multifunctional surface finish, applicable to soldering, press fit connections and as
the interface for Zero Insertion Force (ZIF) edge connectors. The immersion Tin protects the
underlying copper from oxidation over its intended shelf life. Copper and Tin however have a very
strong affinity for one another. The diffusion of one species into the other will occur, forming Cu/Sn
intermetallic (IMC) compounds, thereby impacting to shelf life of the deposit and the performance of
the finish.
The latest generation of Immersion Tin deposits utilize various methods of retarding the diffusion
process, including the use of co-deposition of organics, the use of another metal as a diffusion
barrier or the use of grain structure refining. It is recommended that the user of the deposit clearly
understand the different methods of copper migration retardation and that the supplier know the
positive and negative impacts of the system chosen.
IPC-4554-2005 浸没镀锡印刷电路板规范.pdf

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