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One of the biggest challenges facing PCB designers is not understanding the cost drivers in the PCB manufacturing process. This article is the latest in a series that will discuss these cost drivers (from the PCB manufacturer’s perspective) and the design decisions that will impact product reliability.
Final finishes provide a surface for the component assembler to either solder, wire bond, or conductively attach a component pad or lead to a pad, hole, or area of a PCB. The other use for a final finish is to provide a known contact resistance and life cycle for connectors, keys, or switches. The primary purpose of a final finish is to create electrical and thermal continuity with a surface of the PCB.
There are a number of final finishes in use in the industry today, including:
- ENIG (electroless nickel, immersion gold)
- ENIPIG (electroless nickel, immersion palladium, immersion gold)
- ENEPIG (electroless nickel, electroless palladium, immersion gold)
- IAg (immersion silver)
- ISn (immersion tin)
- Sulfamate nickel/hard or soft gold (Electrolytic nickel/gold)
- HASL (hot air solder leveling)
- SnPb (63/37 tin/lead)
- LF (lead free)
- OSP (organic solderability preservative)
Final finishes are primarily application driven, so there are a number of considerations that should be part of any decision to choose a final finish.
To read this entire article, which appeared in the September 2022 issue of Design007 Magazine, click here.
Nolan Johnson, I-Connect007
Nolan Johnson checks in with Polar’s Martyn Gaudion on the evolving needs of global PCB manufacturing markets in a post-pandemic world, where generating accurate PCB specification documentation is essential to successfully navigating today's rampant supply chain constraints. Polar has positioned itself to meet these needs through agile software product developments that allow OEMs and fabricators to simulate material interactions and end-product specifications, including in-demand features like a comprehensive "structure view" that allows users to visualize all the transmission lines on a given a PCB. Though keeping pace with the demands of a rapidly growing industry has been challenging, Polar's commitment to innovation has kept its software suite ahead of the curve.
Cherie Litson, CID+, Litson1 Consulting
HDI—high-density interconnect—designs require some different thinking on the part of the designer. One of the first things to consider is whether you need HDI, and if so, how much. The HDI option comes into play as soon as you purchase any components with 0.5 mm pin pitch. The number of these components and other specifications of your design will determine the amount of HDI you will need. Here’s a quick list of HDI options.
Happy Holden, I-Connect007
For this issue, Happy Holden provided a range of options for designers who are seeking to conserve materials in their next design. He also offered an example of the relative cost index, or RCI, that he developed at HP exclusively for PCB design. With this RCI, designers can figure out the relative cost of a new design compared to an eight-layer through-hole board. We hope you can use this handy formula on your next design job.