Issue link: https://iconnect007.uberflip.com/i/1533339
12 PCB007 MAGAZINE I MARCH 2025 ability, ensuring strong and stable connections between components, which is essential for the overall functionality of the device. In summary, final finishes are essential for: • Protection: Safeguarding components from environmental damage • Solderability: Ensuring secure and stable connections • Reliability: Extending the lifespan of electronic devices e perennial question always will be: Which finish is best for which application? In the dynamic world of electronics manufacturing, the choice of finish is far from trivial—each type has its distinct advantages tailored to specific applications. In Table 1, the most common fin- ishes and their potential uses are displayed. e table easily makes visible why gold-con- taining finishes are of such big interest for high- end market applications: It's the versatility and reliability of their end-application. Different Gold Types Is the gold electrolyte used for ENIG, ENEPIG, and EPAG always the same? To answer that question, let's dive into the dif- ferent types of gold electrolytes. What kinds of electrolytes exist and what are their prop- erties? What are the advantages and disad- vantages of those different gold bath types in metal plating? For the purposes of an overview, we will divide electroless gold electrolytes into immer- sion-type and mixed-reaction types (Figure 1). For immersion-type electrolytes (I), the elec- trons required for the gold deposition are pro- vided by the nickel dissolution only; for mixed reaction-type electrolytes, the immersion reac- tion is supported by a certain amount of auto- catalytic reaction. e proportion of the auto- catalytic reaction within the overall reaction depends on the type of additive used. In gold electrolytes, where the autocatalytic portion is low (II), the additive typically exhibits mild reductive properties. e major reaction is driven by the dissolution of the nickel layer and the additives have only a supportive function. In the third type of gold electrolytes (III), additives with stronger reducing properties are utilized. e initial stage of gold plating involves an immersion reaction. Once the first Table 1: Characteristics of different final finishes.