In the assembly and soldering process of printed circuit boards (PCBs), we often hear engineers or lab reports mentioning the term “IMC.” But what exactly is IMC? What role does IMC play in the PCB assembly (PCBA) soldering process? Does it impact solder joint strength? People often comment on IMC being too thin or too thick, so what is a reasonable thickness for IMC?
Recently, many have inquired about how to deal with Non-Wet-Open (NWO) issues when encountering BGA packaged ICs soldering. The defects associated with NWO are quite similar to those of HIP (Head-in-Pillow) and typically occur at the edges and corners of BGA packaged ICs. The root cause often lies in the substrate or PCB of the BGA, where the board material may deform due to the high temperatures during the reflow process.
The alloy composition of lead-free LTS (Low Temperature Solder) usually includes the metal “bismuth (Bi)” in addition to tin (Sn) to lower its eutectic point.
The commonly used lead-free solder SAC305 has a melting point of 217°C, while Sn64Bi35Ag1 has a melting point of only 178°C, and Sn42Bi58 has an even lower melting point of 138°C. This means that the melting temperature of solder containing “bismuth (Bi)” is significantly lower, ranging from 39°C to 79°C lower than SAC305 lead-free solder.
The “8D report” is a tool commonly used in the electronics assembly industry for “problem analysis and solving.” Due to its systematic and clear steps, the “8D report” is often utilized in responding to customer complaint cases.
The term “8D” refers to the “8 Disciplines process.” The person filling out the report generally follows predefined steps in sequence. This helps most quality control personnel systematically identify the causes of problems step by step. It also allows you to explain to the customer how the problem was discovered or occurred, how you analyzed the problem, found the root cause, verified if the problem was genuinely resolved, and implemented preventive measures to prevent the problem from recurring.
A Bill of Materials (BOM) is a list of materials required for the production of an electronic product. It serves as an important bridge between the designer, manufacturer, and supplier. The BOM includes all the components, devices, and materials used in an electronic product, with information such as their type, model, quantity, manufacturer, and supplier listed.
