In general, the processes used on electronic assemblies are a series of chemical processes. Each step in the operation has the potential for leaving harmful materials on the PCA that can compromise assembly reliability. Cleaning is often needed to remove such harmful residues and improve reliability. Cleaning is also used to remove residues as an aid to inspection.
Customer contracts often require the assembly to be cleaned and tested for cleanliness!
Most assembly processes will be divided into two general categories:
- those that incorporate a cleaning process and
- those that do not.
Both assembly categories are capable of producing high reliability hardware. The post-soldering cleanliness designator allows a customer or manufacturer to specify the process to be used on their hardware.
The cleanliness of parts is necessary both before and after soldering. Poor cleanliness is a common cause of solderability problems. Effective cleaning after soldering may be necessary to promote good adhesion of conformal coating, prevent leakage paths, and avoid corrosion.
If the assembly has to be cleaned, the user has to clean the assembly (the cleaning solution chosen should remove the harmful flux residues), while leaving the other materials and components alone. The cleaning media should be capable of removing any electrically conductive residues (ionic residues) and non-conductive (non-ionic or organic) residues.
Want to know more about cleaning PCB’s and PCA’s? ETECH Training has a new training course about cleaning PCB’s and PCA’s. In this Cleaning of PCB’s and PCA’s training, you will learn more about the reason for cleaning (Pro’s & Con’s), how clean is “Clean”? and what about No-clean flux? Do we need to clean No-clean flux?
