Why should I give a flux?

RE: Why should I give a flux?

Ian Williams — Wed, 24 Jul 2019 19:25:01 GMT

Hi Jack, this is less of a thermal issue and more of a current leakage issue. The drift is caused by very slow change in current leakage paths on the PCB, but I'm not sure of the physical mechanism of that change.

RE: Why should I give a flux?

JaPaBo — Wed, 17 Jul 2019 01:09:50 GMT

These are very interesting and useful measurements. What is the physical mechanism causing the drift to occur over time? I'm assuming the circuit has minimal self-heating (e.g., ~16 µW in the bridge resistors).

RE: Why should I give a flux?

Kristina Atkins — Thu, 31 Oct 2013 15:22:22 GMT

@Ivan Figueiredo, please re-post your comment in English if you would like a response.

RE: Why should I give a flux?

Ivan Figueiredo — Thu, 31 Oct 2013 15:03:51 GMT

Muito bom o artigo . Muitas vezes o mal funcionamento inexplicado pode ter uma solução simples como apresentada, prática e valiosa . O banho de ultra som poderia ser feito em álcool isopropílico ?

RE: Why should I give a flux?

Ian Williams — Fri, 11 Oct 2013 20:07:37 GMT

Hello Audet, thank you for the question.

You're absolutely right - some components simply can't be immersed in water, even deionized water (which is what the ultrasonic bath should be filled with). Some common examples of this are mechanical switches and some potentiometers. Always check a component's data sheet if you have any question about whether or not it can handle immersion.

On PCBs with sensitive components, what we typically do is assemble the board with all the components that can handle immersion, then clean the board in the bath. After this we'll populate the sensitive components and do the best hand cleaning we possibly can. This has given us good results.

Typically I run my PCBs in the bath for 15 minutes.

Thanks for reading!

RE: Why should I give a flux?

Audet Aubert — Fri, 11 Oct 2013 00:46:07 GMT

About the ultrasonic bath cleaning : Could some sensitive components be damaged by this operation? How many time the PCB stays in the bath?

RE: Why should I give a flux?

Ian Williams — Fri, 04 Oct 2013 19:24:29 GMT

Thanks for the feedback John!

RE: Why should I give a flux?

John Griffith — Fri, 04 Oct 2013 19:06:01 GMT

Good article Ian! Always new cleaning mattered, but never had any measurements to stand by.