Technetters,

	Can anyone offer advice on using a no-flow underfill (fluxing underfill or epoxy flux) on a circuit card assembly?

	I thought underfill was supposed to have a CTE that was close to a compromise between the other CTEs of the assembly (solder, PWB, component) but it seems that all the no-flow underfills have CTEs (55-75 ppm/°C) that are higher than all the other assembly materials. Should I not be worried about this amount of mismatch?


Thanks in advance,
Ben


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