SMT007 Magazine


Issue link:

Contents of this Issue


Page 90 of 94

April 2014 • SMT Magazine 91 bring that resistivity to a normal and accept- able level. By changing the chemicals used for cleaning, the resistivity is broken down. Thus, a clean surface is created which is acceptable to the customer. Certain automated devices perform ROSE testing, including Omega, Ionograph, and Zero Ion meters.. Once boards are cleaned, these me- ters provide results in part per area (PPA) clean- liness to comply with IPC standards. ROSE testing has certain limitations. It only performs ionic contamination test; not non- ionic. It measures average contamination for an assembly, but doesn't define the source. Certain board parts are more contaminated due to extra touch up or rework. Therefore, there's more flux in those areas compared to other parts not get- ting as much rework. This means the amount of contamination is different at different board sections. However, ROSE test deals with average assembly contamination and provides average results of the overall surface of the board. IPC Standard TM650 is the most common test. The board is dipped into a water-based sol- vent with a great percentage of alcohol at cer- tain temperatures and time periods. Different parameters can be changed in this testing stan- dard. Temperature, as well as alcohol and water concentrations can be changed. Different levels can be checked also. Those measurements in- clude the fluoride, chlorine, bromide, nitrate, phosphates, sulfate, and organic acid. Multiple factors can be measured. Meanwhile, SIR measures the effective- ness of contaminants remaining on a board. An electrical test runs currents from point-to- point. Those contaminants are measured at cer- tain temperature and humidity levels. When the characteristics are read, the test character- izes residues or fluxes and other contaminants left on a board. Monitoring and qualifying the degree of cleanliness is absolutely important to make sure final assemblies are acceptable per IPC Class 3. There is some ambiguity in Class 3. However, there are a number of techniques deployed in terms of cleaning the PCBs, many are common- ly used in electronics manufacturing in con- ventional ways. Other cleaning techniques are in R&D, al- though newer cleaning products are coming on the market. But the point is cleanliness test- ing is critical. Ionograph testing and the other methods discussed above can best perform that testing. SMT Zulki khan is the founder and president of nexlogic Technologies Inc. To read past columns, or to contact the author, click here. TiGhTEr SCrUTiNY NEEDED FOr pCB ClEaNiNG aGENTS continues Technology expert Cary Hayner says his com- pany has developed battery materials that can store about 10 times the amount of energy that a lithium-ion bat- tery does, potentially changing the future of energy storage in products such as cell phones and electric cars. "This year, 2014, we are fo- cusing on developing our first prototypes that would go into future generations of some of these boutique cell phones," said Hayner, the chief technol- ogy officer of Sinode Systems. "These wouldn't be the huge general-consumer type of devices right now." Hayner joined a four-expert panel to discuss the future of energy storage efficiency which included representatives from Argonne national labs, Sinode Systems, navitas Systems, and Intelligent generation. from cell phones to electric cars to military missile technology, batteries play a crucial role in today's society, according to the experts. technology extends Life span of Batteries Zulki'S PcB nuggeTS

Articles in this issue

Links on this page

Archives of this issue

view archives of SMT007 Magazine - SMT-Apr2014