-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueLevel Up Your Design Skills
This month, our contributors discuss the PCB design classes available at IPC APEX EXPO 2024. As they explain, these courses cover everything from the basics of design through avoiding over-constraining high-speed boards, and so much more!
Opportunities and Challenges
In this issue, our expert contributors discuss the many opportunities and challenges in the PCB design community, and what can be done to grow the numbers of PCB designers—and design instructors.
Embedded Design Techniques
Our expert contributors provide the knowledge this month that designers need to be aware of to make intelligent, educated decisions about embedded design. Many design and manufacturing hurdles can trip up designers who are new to this technology.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - design007 Magazine
DFM 101: Final Finishes ImmSn
December 29, 2022 | Anaya Vardya, American Standard CircuitsEstimated reading time: 1 minute
Introduction
One of the biggest challenges facing PCB designers is understanding the many 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
The primary purpose of a final finish is to create electrical and thermal continuity with a surface of the PCB. 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. Another use for final finishes is to provide a known contact resistance and life cycle for connectors, keys, or switches.
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)
- ImmAg (immersion silver)
- ImmSn (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:
- Lead (Pb) tolerant or lead-free (LF) process
- Shelf life
- Flatness
- Lead or ball pitch
- Wire bondability
- Lead insertion
- Solder joint integrity
- Corrosion resistance
- Potential problems
- Cost
Lead-free finishes are considered RoHS-compliant (< 0.1% BW of finish, for Pb, Hg or Cd) with the single exception of tin/lead HASL. The RoHS-compliant finishes include the following:
- ENIG
- ENIPIG
- ENEPIG
- ImmAg
- ImmSn
- Electrolytic nickel/gold
- LF HASL
- OSP
Lead-free PCBs require that the standard HASL surface finish cannot be used. There is still a significant amount of discussion on what the long-term surface finishes will be. Currently, the immersion silver and OSP surface finishes are the most prevalently specified surface finishes for solderable PCBs. Immersion tin is the prevalent surface finish for press-fit backplanes. Please contact your PCB fabricator for current information on where industry specifications are heading.
To read this entire article, which appeared in the November 2022 issue of Design007 Magazine, click here.
Suggested Items
Indium Corporation Expert to Present on Pb-Free Solder for Die-Attach in Discrete Power Applications
04/30/2024 | Indium CorporationIndium Corporation Product Manager – Semiconductor Dean Payne will present at the Advanced Packaging for Power Electronics conference, hosted by IMAPS, held May 8-9 in Woburn, Massachusetts, USA.
Taiyo Circuit Automation Installs New DP3500 into Fuba Printed Circuits, Tunisia
04/25/2024 | Taiyo Circuit AutomationTaiyo Circuit Automation is proud to be partnered with Fuba Printed Circuits, Tunisia part of the OneTech Group of companies, a leading printed circuit board manufacturer based out of Bizerte, Tunisia, on their first installation of Taiyo Circuit Automation DP3500 coater.
Vicor Power Orders Hentec Industries/RPS Automation Pulsar Solderability Testing System
04/24/2024 | Hentec Industries/RPS AutomationHentec Industries/RPS Automation, a leading manufacturer of selective soldering, lead tinning and solderability test equipment, is pleased to announce that Vicor Power has finalized the purchase of a Pulsar solderability testing system.
AIM Solder’s Dillon Zhu to Present on Ultraminiature Soldering at SMTA China East
04/22/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce that Dillon Zhu will present on the topic: Ultraminiature Soldering: Techniques, Technologies, and Standards at SMTA China East. This event is being held at the Shanghai World Expo Exhibition & Convention Center from April 24-25.
AIM to Highlight NC259FPA Ultrafine No Clean Solder Paste at SMTA Wisconsin Expo & Tech Forum
04/18/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce its participation in the upcoming SMTA Wisconsin Expo & Tech Forum taking place on May 7 at the Four Points by Sheraton | Milwaukee Airport, in Milwaukee, Wisconsin.