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The Plating Forum
Column from: George Milad
George Milad has 30+ years of experience in PWB manufacturing and is the national accounts manager for technology at Uyemura International Corporation. He holds a master’s degree in physical organic chemistry from the American University in Washington, D.C., 1979, is the author of the chapters on plating and surface finishing in _Printed Circuits Handbook: Seventh Edition_, and has a series of publications on electrolytic plating and metallic surface finishes. George is the recipient of the 2009 IPC President’s Award, chairs the IPC Plating Committee, and is a permanent member of the IPC Technical Activities Executive Committee.
June 20, 2023
The Plating Forum: Reduction Assisted Immersion Gold for ENEPIG Surface Finish
RAIG was introduced a few years ago to meet the requirements of newer designs. Since its inception more gold finishes are finding RAIG to be a viable alternative to standard immersion gold. RAIG is a mixed reaction bath that functions as an immersion gold and, with the added reducing agent, it also functions as an electroless (autocatalytic) bath.November 15, 2022
The Plating Forum: Surface Finish Evolution from Conventional to Advanced
Surface finish is a critical component in printed circuit board (PCB) design and functionality. Surface finishes form the interface between the component and the circuitry. As its most essential function, the final finish process is intended to provide exposed copper circuitry with a protective coating to preserve solderability. Select surface finishes are also used for wire bonding or as an electrical contacting surface. Perhaps no other step in the PCB manufacturing process has undergone more change in the era of surface mount manufacturing than the final finish chemical process.July 06, 2022
The Plating Forum: Plating in Electronic Applications
Plating is the deposition of a metal layer on a substrate in order to modify its properties. It occurs when the metal ion in an aqueous solution is reduced to the metal: M+ metal ion + e- reducing electron = M0 deposited metal. Plating can achieve numerous functional and aesthetic goals, including: improve solderability, inhibit corrosion, increase hardness/durability, decorate objects (jewelry), reduce friction, alter conductivity, improve IR reflectivity, provide radiation shielding.March 30, 2022
The Plating Forum: How the Pandemic Impacted PCB Manufacturing
The coronavirus pandemic has had a major impact on PCB manufacturing and assembly. Thanks to its classification as an essential business associated with national security, PCB manufacturing in the U.S. was exempt from shutdowns; it was not, however, immune from supply chain disruption. Raw materials shortages set the stage for higher prices. Companies that relied on just in time (Kanban) inventory management held back product, further burdening the supply chain.November 24, 2021
The Plating Forum: The Significance of IPC ENIG Specification 4552 Revision B
The ENIG specification 4552 was issued in 2002. Since then, it has gone through a series of amendments and revisions in an attempt to meet the everchanging industry requirements. It started as a thickness specification that did not mention lead-free soldering or “nickel corrosion” and ended in the latest performance specification 4552B where all aspects of nickel corrosion were addressed. Suppliers now have a way to evaluate the performance of products in the field. They can increase the robustness of their products and service to ensure that customers can produce acceptable ENIG finishes in different manufacturing environments.October 06, 2021
The Plating Forum: The IPC Surface Finish Specifications
Specifications are reference documents to be called out by OEM board designers in specifying the attributes of a surface finish. Designers may take exception with one or more items in the specification to ensure that the product meets the requirements of its intended use. The term “AAUBUS” (As Agreed Upon Between User and Supplier) is part of any specification.September 06, 2021
The Plating Forum: An Overview of Surface Finishes
Surface finishes’ research and development departments on the supplier side have been very busy coming up with new finishes to meet the everchanging demands of the electronics industry. Today, designers have wide variety of finishes to choose from. George Milad breaks it down.June 16, 2021
The Plating Forum: DIG—The Next Generation
DIG stands for “Direct Immersion Gold.” The acronym is used to specify direct deposition of gold on copper as a surface finish. It is a metallic solderable finish. At assembly, DIG forms a Cu/Sn intermetallic with the gold layer dissipating into the bulk solder.April 05, 2021
The Plating Forum: RAIG (Reduction Assisted Immersion Gold) for Gold Surface Finishes
RAIG was introduced a few years ago to meet the requirements of newer designs. Since its inception, more gold finishes are finding RAIG gold to be a viable alternative to standard immersion gold. RAIG gold is a mixed reaction bath that functions as an immersion gold and with the added reducing agent it also functions as an electroless (autocatalytic) bath.December 24, 2020
The Plating Forum: Training for Plating Processes in the Electronics Industry
Plating is a very old industry and has been studied for many generations. Its basic principles are well understood and documented. However, when it comes to the intricate details of plating a circuit board, there is so much to learn and apply. George Milad explains.November 19, 2020
The Plating Forum: Via Plating for PWBs
Vias are an integral part of PWB design and manufacturing. They are the means by which different layers of a board are connected. George Milad addresses the electroplating of vias, including the three main types of vias: through-hole vias, buried vias, and blind vias.October 22, 2020
The Plating Forum: The Critical Role of Pretreatment for Plating
Pretreatment is usually customized to the incoming substrate and the plated metal. George Milad explains how it is a critical step and must be completed before plating to achieve the desired adhesion and to enhance the quality of the deposited metal.September 16, 2020
The Plating Forum: Immersion Plating Reaction in Electronics Manufacturing
Plating or metal deposition is a key component in the manufacturing of electronic packages (circuit boards and integrated circuits). Plating occurs when a metal ion in solution (electrolyte) is reduced to the metal. The reduction takes place when electrons are supplied to the ion. George Milad dedicates this column to the immersion reaction.March 15, 2020
The Plating Forum: Eliminating Waste From Electrolytic Acid Copper Plating
Acid copper plating in most shops is done in vertical plating tanks. Acid copper solutions are not dumped but are continuously used with occasional carbon treatment to remove organic build-up from the additives and from dry film leaching. George Milad explains.July 06, 2020
The Plating Forum: Minimizing Signal Transmission Loss in High-Frequency Circuits
All PCB materials have both conduction and dielectric RF signal losses. In this column, George Milad highlights resistive conduction losses by the copper layer used in the board.May 25, 2020
The Plating Forum: Can ‘Nickel Corrosion’ Occur in ENEPIG?
Nickel palladium gold (ENEPIG) surface finish is being referred to as the “universal finish.” ENEPIG was also the answer to the nickel corrosion “black pad” encountered occasionally with electroless nickel/immersion gold (ENIG) deposits. In this column, George Milad answers the question, "Can 'nickel corrosion' occur in ENEPIG?"January 11, 2020
The Plating Forum: EPIG—A Nickel-free Surface Finish for Next-generation Products
In recent years, electronic devices, such as smartphones and tablet PCs, have been miniaturized. Chip-size package (CSP) used inside the electronic devices have been miniaturized as well, and the spacing between the lines continues to diminish every year. Some of the latest packages have spacing as little as 15 µm or less. If electroless nickel electroless palladium immersion gold (ENEPIG) is used with an EN thickness of 5–6 µm, only 5 µm of spacing would be left, increasing the risk of shorts between the traces. George Milad explains.January 08, 2020
The Plating Forum: New Developments in ENIG
ENIG has been around the printed circuit industry for more than 25 years. George Milad provides an update and explains how although the occurrence of corrosion was recognized, a better understanding of the defect has led to a series of improvements over time.October 20, 2019
The Plating Forum: Update on IPC-4552 ENIG Specification Revisions
George Milad's columns will cover PCB plating, IPC specifications, and more. In this debut installment, he gives us an update on the IPC-4552 ENIG specification, including Revision A and B.March 05, 2014
The Plating Forum: Wire Bonding to ENIG
The IPC-4552 ENIG specification was written in 2002, but the committee is currently updating and revising the document. The thickness of the immersion gold layer is being revised with the intent of reducing the minimum thickness from 2.0 µin to 1.6 µin. A series of studies were conducted to find out if this reduction is possible.January 07, 2014
The Plating Forum: ENIG and the Plating Process
ENIG continues to gain market share due to its versatility in a wide range of component assembly methods including solder fusing, wave soldering, and wire bonding. The plating of ENIG is a complex multi-step process. Each process step is carefully designed and must be well understood and controlled to produce the desired end product. George Milad reports.July 16, 2013
Acid Copper Plating for High Aspect Ratio and Via Fill
To meet new specification requirements, board shops are forced to seek new and advanced processes in every department. Acid copper plating comes under heavy scrutiny, as it is the process that forms the traces and the through-hole connectivity that conveys the signal from end-to-end of the final device. George Milad, a new columnist for The PCB Magazine, explains.
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