Technical Cleanliness: Contamination Cleaning

[Vignesh Devadas]

1. Even though everything is manufactured in a cleanroom, there will be processes which will create contamination like milling, screwing and soldering. How is the cleanliness of the component maintained? 100% clean?
2. When there are IC Pins with a span of just 200µm, how to prevent a short circuit from particles as small as 200µm or more. Which is the best cleaning method? (There is no cleanroom at this stage.) I know using IC test we can make sure that PCB is free from short circuit but we are transporting and coating it in a separate line. How to make sure there are no particles bigger than 200µm is present in the PCB.
3. After selective soldering process, how can we get rid of the solder balls (through Automated cleaning and no manual cleaning)
4. Is there a dry cleaning process, which can make sure that cleans the electronics 100% free of all particles bigger than 200µm or 400µm.?

Product conditions: Always Dry, Humidity and room temperature is maintained as per norms. No cleanroom. Automation-friendly process,

 

[davenn]

Even though everything is manufactured in a cleanroom, there will be processes which will create contamination like milling, screwing and soldering. How is the cleanliness of the component maintained? 100% clean?

that's why they call it a clean room

After selective soldering process, how can we get rid of the solder balls (through Automated cleaning and no manual cleaning)

most soldering process is done by solder bath/wave soldering these days

 

[Harald Kapp]

most soldering process is done by solder bath/wave soldering these days

THT: yes.
I say most SMD components are reflow soldered with a comparatively low risk of stray solder balls.

 

[kellys_eye]

2. Solder masks. NDT (pin board). Optical sensing etc.

SMD IC's would be most prone but as mentioned, solder masking and the reflow oven procedure should prevent any of that happening.

 

[Vignesh Devadas]

that's why they call it a clean room

A cleanroom is used to prevent the environmental effects. The particles entering from the outside. But if the process itself creates contamination, how do you clean is very perfectly.

 

[Vignesh Devadas]

THT: yes.
I say most SMD components are reflow soldered with a comparatively low risk of stray solder balls.

But because of cost factors, it is decided to do selective soldering, in this case how to clean the solder balls.

 

[Vignesh Devadas]

2. Solder masks. NDT (pin board). Optical sensing etc.

SMD IC's would be most prone but as mentioned, solder masking and the reflow oven procedure should prevent any of that happening.

As I mentioned above, only selective soldering is possible. In this case how to clean the solder balls automatically

 

[kellys_eye]

Solder balls will only adhere due to residual flux which should be washed off after any soldering process anyway.

Solder balls that adhere to other solder (or tracks) won't move anyway so will be of no concern.