The purpose of cleaning printed circuit boards is to remove conductive particles, flux, dust and other residues, achieve insulation, prevent poor contact, prevent poor contact of contact feet during path testing, prevent corrosion, etc. Therefore, the evalsuation of PCBA cleaning is particularly important, which directly affects the quality of PCBA after cleaning. Therefore, this article evalsuates and analyzes the effectiveness of PCBA cleaning as follows.

(1) Reliability evalsuation

It is necessary to pre evalsuate the reliability of printed circuit boards after cleaning when citing cleaning techniques and equipment.

We will use a reliability testing specific test printed circuit board for insulation testing evalsuation, and use a pressure furnace for accelerated testing in terms of environment.

(2) Impact on components

Electronic components have a certain compatibility with cleaning agents. Various different test components or materials are selected for cleaning tests and pre evalsuation is carried out. Especially for resin based electronic components, discoloration or expansion may occur due to the action of cleaning agents, printed text may fall off, water may seep into the components, and water accumulation during component installation should be carefully evalsuated.

During the drying stage using hot air heating, due to the thermal stress on the components, it is necessary to confirm the heat distribution on the surface of the components through inspection.

During the drying stage using hot air heating, due to the thermal stress on the components, it is necessary to confirm the heat distribution on the surface of the components through inspection.

Common evalsuation test methods:

When determining the specific specifications of each cleaning process, a comprehensive evalsuation of the above issues must be conducted. The commonly used evalsuation test methods are as follows:

① Visual inspection items can be directly visual, microscopic, or ultraviolet visual. By observing and determining the target of interest through visual inspection, PCBA can be evalsuated for foreign objects or types of foreign objects.

② Ionic residue extraction test items generally use dynamic or washing methods, including ion radiation cameras or ohmmeters. At present, the quality of assembled boards is often evalsuated based on the US military standard MIL-P-28809 after cleaning.

③ The electrical inspection and evalsuation test project mainly involves testing insulation resistance and conductivity, which can refer to the Japanese industrial standard JISC5012.

④ The moisture resistance test items are environmental tests, mainly including constant test, cyclic test, pressure pot test, etc.

⑤ The solvent resistance test project for electronic components mainly tests the compatibility of components and the printing strength of characters. The main content is to carry out cleaning under specified operating conditions, evalsuate whether there is color change and blistering, and pay attention to whether the printed or printed characters have faded or disappeared.