Wickham, M; Zou, L; Hunt, C (2002) An assessment of the suitability of current PCB laminates to withstand lead-free reflow profiles. NPL Report. MATC(A)91

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Abstract

Five different aspects of PCB manufacture and processing have been investigated to explore whether the move to the hotter reflow profiles associated with lead-free soldering would affect the performance of four common laminate types (i.e. BT epoxy; polyimide; high Tg epoxy). Boards of the different laminates were subjected to multiple cycles of temperature profiles representative lead-free soldering, and then studied in relation to dimentional stability, bend testing, surface insulation resistance, surface composition and solderability.
The work has highlighted two areas of concern if current laminate types and immersion gold pcb finishes are used in lead-free soldering technologies. First, if a board is going to be subjected to stresses during the lead-free soldering operation, then manufacturers wishing to have a flat, or near flat, assembly after soldering, should consider whether or not the Tg of the base laminate material is appropriate. Second, the lower soldering yields after more than a single lead-free soldering operation, suggests that more aggressive fluxes must be used to maintain soldering yield.
The increased temperatures of lead-free soldering had little or no effect on dimensional stability or surface insulation resistance of the laminate materials studied.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)91
Keywords:	PCB reliability, PCB stability, surface insulation resistance, solderability
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2396

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