About the advantages and disadvantages of tin-plated circuit boards

2019-10-22 17:08:42 Juding Circuit Technology

Pcb manufacturers (Juding Circuit Technology) for your analysis: the advantages and disadvantages of spray tin pcb circuit board.

The tin-spraying process board is a relatively common type of PCB board, generally a multi-layer common high-precision circuit board, and its process boards are widely used in various types: small household appliances, consumer electronics, intelligent electronics, electronic equipment, beauty electronics. , communications products, computers, industrial equipment, medical equipment, automotive electronics, aerospace electronics and other related electronic products.

Then: What are the advantages and disadvantages of lead-free tin-plated PCB boards?

Spraying tin is a step and process flow of PCB board in the production process. The process is to immerse the PCB board in the molten solder bath. All exposed copper surfaces are covered by solder, and the PCB board is passed through the hot air cutter. Excess solder removal. The surface of the PCB circuit board after tinning is the same kind of material as the solder paste, and the welding strength and reliability are better. Due to the characteristics of its processing technology, the surface flatness after tin-spraying treatment is general, especially for the precision electronic components of the package type BGA, because the welding area is small, such as the flatness is not good, it is easy to cause short circuit and so on, so A relatively flat process is required to solve the problem of unevenness of the tin plate. General customers will choose the chemical gold process (note that the chemical gold process here is not a gold plating process), reworking with the principle and method of chemical displacement reaction, increasing the nickel layer with a surface thickness of 0.03~0.05um or 6um, and improving the PCB soldering. The surface of the disc is flat.

Its advantages:

The wettability of the components during the soldering process is better, and the soldering is better. The copper surface exposed to the pad can be prevented from being corroded or oxidized.

Its disadvantages:

It is not suitable for the pins used in the soldering gap and the components that are too small. The surface of the tin plate is relatively flat. It is also easy to produce tin beads in the processing of PCB boards, and the components of the inter-gap pins are more likely to cause short circuit. When used in the double-sided SMT chip process, the first side has been subjected to a high-temperature reflow soldering, which is prone to re-melting of tin to produce tin balls or solder balls similar to water droplets that are affected by gravity, causing surface irregularities and thus affecting SMT patch soldering.

Of course, with the continuous advancement of technology, PCB board manufacturing has been applied to PCB board manufacturing processes suitable for assembling tin-casting processes such as QFP and BGA with smaller pitches, but the practical application is relatively small. At present, some PCB board manufacturing adopts OSP process and immersion gold process to replace lead-free tin-spraying process. From the technical development, some factories adopt the process of sinking tin and sinking silver. With the trend of lead-free in recent years, spray The use of tin technology has also been further limited.