Printed Circuit Design & Fab Online Magazine
Gold utilized in circuit board floor treatment, because the conductivity of gold is powerful, good oxidation resistance, lengthy life, basic functions such as key board, finger board, etc. The basic distinction between gold plating and ENIG is gold plating is tough gold , ENIG is gentle gold .
These have been the mainstay of the business so processing gear, solder pastes, fluxes, solder masks, and even stencil inks were designed to deal with these processing profiles. Given that hard plating includes nickel, iron, cobalt and different non-noble metals, soldering of hard gold is rather more troublesome than with ENIG plating. If you’re planning to undertake ultrasonic wire bonding, thermostatic bonding or different sensitive becoming a member of, onerous plating makes the method extraordinarily troublesome.
Hard gold plating sometimes contains the smallest possible grain sizes, which run 20 to 30 nanometers, and its hardness runs between a hundred thirty and 200 HK25. These characteristics make hard plating’s surface finish much more lustrous than ENIG plating.
Hard plating can stand up to applications that assert 50 grams of contact drive or more. Hard plating can stand up to much more cycles than ENIG plating as properly, with the exact number of cycles dependent on the thickness of the plating. High production costs and a risk of nickel oxidation-related defects before the immersion in the gold which causes some points when soldering BGAs. Following the application of the RoHS directive in 2006, the disappearance of lead from printed circuits led to the looks of many finishing alternatives. On the one hand, they make it attainable to avoid utilizing lead anyplace within the course of, and on the other to create thin coatings and small spacing.
Typical thicknesses are u” of nickel adopted by 5 u” palladium after which 1-three u” gold. There is a value premium over ENIG but the advantages might far outweigh the value enhance. The oldest PCB used finishes are 60Sn/40Pb solder (easily soldered at average temperatures however lead-containing) and OSP .
Rapid oxidation of the electroless nickel phosphorous layer when careworn with warmth and moisture explains the superior EPIG result. The value enhance with ENEPIG in comparison with Pb-free HAL is important but when it does the job, it is nicely worth the fee. On the opposite hand a 28% premium for ENEPIG or even the modest 14% enhance with ENIG could be cash wasted in case your components don't demand the flattest of pads. Consider the processing parameters of your BoM early within the design course of as their floor requirements will significantly affect the overall board price. The most up-to-date advance in surface preparation is ENEPIG, electroless nickel/electroless palladium/immersion gold.