PCB Fabrication

Pcb Loss Comparisons Between Enig Coating

by:A-TECH      2020-10-30

Effects of thermal processes, cleaning strategies, soldering, parylene deposition and manufacturing unit cleanliness have been examined completely. The resulting evaluation revealed a extremely porous electroless nickel coating with deep crevasses and fissures penetrating right down to the base copper layer. These open nickel boundaries had been attributed to the corrosive environment inside ENIG plating, which resulted within the pad floor discoloration. The root explanation for ENIG pad discoloration and pitting was traced back to poor ENIG line course of controls.

Microstrip copper strains play an important function in high-velocity printed circuit boards. It is necessary to perform applicable surface finishing on the microstrip copper strains to avoid oxidation and cut back the lack of sign transmission. In this work, the microstrip copper strains after micro etching therapy were finished with immersion silver, immersion tin and electroless nickel immersion gold , respectively.

Surface microstructures, 3D features and surface contact angle have been examined to search out the impact of the copper finishing on signal transmission loss. The outcomes indicated that the microstrip copper strains with micro-etching treatment reveals low signal transmission loss as − 39.9 dB/m at 20 GHz. The examined microstrip copper lines showed that sign transmission loss follows an growing trend successively with micro etching remedy, immersion silver therapy, immersion tin treatment and ENIG remedy. Initially all processes became suspect, from the bare printed circuit board , to meeting, the flux, the solder, the plating, and so on.

Among these objects, the number of floor end belongs to the primary class as surface end performs an especially significant role in contributing to the reliability of electronic products. As copper layer on PCBs may be easily oxidized, the generated copper oxidation layer will significantly scale back soldering quality, which is able to decrease reliability and validity of the tip products. Surface end is conductive to forestall pads from oxidation and guarantee glorious solderability and electrical efficiency. Manifestation of such latent anomaly was observed in the form of ENIG pad discoloration with variations from yellow, pink or grey discolored surfaces to a more pronounced plating degradation, corresponding to corrosive pitting. The launched failure evaluation concerned analysis of manufacturing processes suspected to contribute to the cause of the condition.

The HASL course of can add stress to high layer circuit boards which may trigger long-term reliability points. This added stress, along with uneven solder peak on dense SMT or BGA pads, are good reasons to replace HASL. Inevitably, tighter design standards, advancing applied sciences, and/or environmental legislation will force the replacement of HASL. There are lead free alloys which might exchange the standard 63Sn / 37Pb solder on this course of, however there are still functionality limitations that exist inside this course of.

At the time, the ongoing push to RoHS compliancy was forcing process changes in all areas without proper validation or verification of said processes. It was turning into evident that immersion gold would ultimately be the lead free floor end of selection. Today, ENIG is the most well-liked surface finish with its outstanding reliability and flat end. The 63/37 tin lead solder has been the business-standard since the inception of the unique circuit board. If lead-free is not a priority, HASL is a very value effective, reliable surface end utilized in the manufacturing of lower expertise PCBs.

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