In this standard the inorganic ions are broken down whereas previously only sodium chloride was mentioned.

In 2010, IPC released IPC-5704, a cleanliness requirement for unpopulated printed boards, aka bare boards. IPC-5704: iPC cleanliness standard for Unpopulated boards It is ultimately the designer's decision, and though using the military standard as a baseline is a good start, it should be seriously revisited with higher technology boards.Д¬leaner finishes such as ENIG, are beneficial inВ attaining a cleaner PCB When testing finished bare circuit boards for ionic cleanliness, IPC 6012 states that the PCB will be tested per Resistance Of Solvent Extraction (ROSE) method, and meet procurement documentation. The fear was that high levels of ionic contamination entrapped underneath solder mask, would affect the solder mask adhesion, leading to blistering, voiding, and peeling of solder mask. The military specification, however, was originated for bare board production panels BEFORE the application of solder mask. Surprisingly, many circuit board assemblers continue to not address PCB cleanliness with their bare board fabricators or they rely on board cleanliness specifications, set by the military, over 30 years ago.Д¬urrently the specification reads 'the contamination level shall not be greater than an equivalent of 1.56 Вµg/cm2 (10.06 Вµg/in2) of sodium chloride.' Many prints and drawings still have that statement as the overall final cleanliness of the bare board, as supplied. These dendritic growths, which were minimal over periods of time, were not a concern of 'yesterdays' bare boards.ДЄs conductor widths and spacing continue to shrink, ionic contamination that propagates dendritic growth becomes much more alarming. Electrochemical migration is the dissolution and movement of metal ions in presence of electric potential, which results in the growth of dendritic structures between anode and cathode. Inorganic contamination within printed circuit board fabrication can lead to electrochemical migration.

Cleanliness of bare circuit boards increases in importance with advances in PCB technology that continue to decrease conductor spacing.

Dendrite growth pcb