How clean is clean when it comes to printed circuit boards and assemblies? While John Perry, IPC technical project manager, can enumerate a litany of complex variables that come into play with an answer to that question, a new cleaning standard, IPC-5704, Cleanliness Requirements for Unpopulated Printed Boards, defines the recommended requirements for the cleanliness of unpopulated single, double-sided and multilayer printed boards.

A vital complement to the June 2007 release of IPC-5702 which describes factors to consider when determining what tests to run for assessing the impact/risk of residues on long-term life (e.g., end-use environment, design/service life and technology involved), IPC-5704 provides the hard specifications and requirements for maximum limits of ionic contamination using ion chromatography testing. In addition, IPC-5704 delivers industry guidance on cleanliness testing for both product acceptance and process control, verifying that all equipment and chemistries are stable.

“The cleanliness of a printed board can directly impact the effectiveness or quality of an assembled printed board,” explains Perry. “Residues increase the risk of field failures or can electrically impede a printed board’s function, so having acceptance criteria for various levels of testing as well as direction on how many samples should be tested is extremely important.”

Referenced in the new cleanliness standard, IPC-TM-650 Method 2.3.28.2, Bare Printed Board Cleanliness by Ion Chromatography is the new test procedure that should be used in conjunction with IPC-5704 to measure the level of anionic and cationic residues on the surface of unpopulated (bare) printed boards by ion chromatography.

Details of the new publication and ordering information can be found on Electronics.ca Publications' web site. View the Cleanliness Requirements for Unpopulated Printed Boards.