Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

RMA vs No clean



RMA vs No clean | 16 January, 2003

I've a query. I have one new Customer whom insisted us to use RMA paste on their product. The problem is, on some of their products they use via hole as the test point in where all the PCB finished are ENTEK and as usual I have to print solder paste on this points to ensure the point is not oxidized after reflow. I have to quitely run a few brds with No-clean paste just to compare the yield at ICT for data collection purposes. I've noticed tremendous improvement on the yield. I'm sure this gotta do with the solid flux that prevented the probes contact to the testpoint. Does anybody have similar experience on this ? Can somebody give me a technical explainations of to why this is so, OR why is the no-clean flux does not hv this problem when they also left the solid flux on the solder formation ?

Pls help. I need some input to convince my customer to change to no-clean.

Thank you

reply »

Mike Konrad


RMA vs No clean | 16 January, 2003

You are comparing apples to oranges. No-clean fluxes, because they are designed not to be cleaned off after reflow, contain very low solids. Normally, no-cleans have a solids content of 2% - 5%. Your basic RMA has a solids content of 15% to 30% (some, even as high as 60%).

A 2% - 5% solids flux, will not leave behind the sticky, gooey, resin that an RMA will (although it will leave behind other forms of contamination). RMA is by nature, designed to be cleaned off after reflow. If your customer is specifying RMA, they are assuming that you are cleaning the board. Otherwise, the boards may also be used as fly-paper.

You only have two choices.

# 1: Talk the customer into no-clean. # 2: If using RMA (or OA), clean the boards before testing.

Mike (909) 944-7771

This message was posted via the Electronics Forum @

reply »



RMA vs No clean | 16 January, 2003


I have a funny feeling that Mike Konrad and I know each other from IBM-Endicott days, yet I could be wrong. It would be funny??

Mike gave a good answer.

The Rosin or Rosin Mildly Activated Flux (RMA) if on the board at ICT (In Circuit Test) will create a probe contacting problem, depending on your process and the time in takes to get to ICT. You can break through (normally) yet the probes pressures and back of board supporting pressures have to be higher.

If you look at Mike's note it is the solid's content that is making break through by the probes harder with RMA vs No-Cleans.

Why does your customer want RMA?

My guess is that the components require RMA to create an acceptable solder joint. Yet I could be wrong.

YiE, MA/NY DDave

This message was posted via the Electronics Forum @

reply »

Capillary Underfill process

Flexible high speed pick & Place