PCB tinning is the process of coating copper traces with layers of tin, which will prevent it from any possible degradation, oxidation, or corrosion. The tin plating will also help mask copper traces while the circuit board itself is being etched.
Benefits of PCB tinning
Doing this simplifies the manufacturing process and also prevents unwanted etching. The industrial method of manufacturing printed circuit boards uses strong solvents like sodium sulfate. Tinning will facilitate this since the risk of corrosion is much lower when a printed circuit board is tinned.
Also, the cost of placing copper traces with higher thickness levels on circuit boards with small current areas is much higher than usual. It is another reason why PCB tinning is preferable; it will save money, especially when there is a high existing path bridge.
Is it possible to do PCB tinning from scratch?
Contrary to popular belief, and contrary to what other PCB manufacturers would tell you, it is indeed possible to perform PCB tinning with household items from scratch, in a DIY type fashion. It does take some effort and the right amount of chemistry knowledge to create the solution necessary to form the tin, but it is possible. DIY PCB tinning is similar to creating a printed circuit board from scratch in that it is possible to create one with a combination of everyday materials as well as materials specific to printed circuit boards. Before exploring these methods, it is useful to understand the PCB tin plating process.
What is the process of PCB tinning?
How PCB tinning is performed?
As the name suggests, PBC tinning utilizes tin. The question is how this tin is used to mask the copper traces in a printed circuit board. The tinning process does indeed use pure tin. However, it also uses a soldered container, a mixture of lead and tin, mixed at a 60:40 ratio. Pure tin and soldered tin are what make up the base of the PCB tinning solution.
The electroplating method of PCB tinning
There are many ways to tina printed circuit board physically, but the most common method is called the electroplating method. In this method, the circuit board is placed in a tin plating station. When this happens, the tin electrodes are introduced into the controlled current flow. It completes the first coating of soldered tin.
After the printed circuit board itself is entirely produced, the second coating of a tin can be applied. To create the second coating of tin, even more soldering must be done. The soldered layers of the container can be deposited either by hand or by a hot solder extruder, which will collect the soldered tin onto the area.
It will resemble liquid, which, if soldered correctly, will dry quickly as it is poured onto the copper trace. Like copper, the tin will also oxidize if exposed to outside environments. One of the reasons solder masking is applied is not to leave the circuit board unmasked.
What PCB tinning solutions are made of?
The Tinning solution is made up of many materials. Some of these materials are everyday items that can be bought locally, and some of these materials need to be purchased from merchants who specialize in PCB and PCB tinning materials.
While not all of these materials are necessary to make a tinning solution, select materials are indeed needed. Because so many variables go into a tinning solution, there are also many different ways to create PCB tinning from choose materials.
Thiourea – The essential ingredient for PCB tinning
The tin plating solution is made of the silver polishing agent, which is commonly used to clean jewelry. One thing that many do not know is that silver polish contains a compound called thiourea, which is the most necessary agent necessary for creating a tinning solution. Thiourea is combined with other materials to create a tinning solution. Without extracting the thiourea from silver polish, making a tinning solution from scratch is impossible.
Thiourea is so active on its own as a compound that it can create electroless tin plates with it that do not require a charge to conduct electricity. Since silver polish can be bought from a typical store, it is possible to at least create the base of any given tin plating with everyday items. However, not every tin plate is designed the same, and to make things even more complicated, each tin plate has different functions.
Other ingredients that will assist in creating a tinning solution
While thiourea is necessary to create a tinning solution, other materials will make creating a tinning solution a much easier process. The first of these is hydrochloric acid, which is also known as muriatic acid. Although this cannot be purchased directly as a silver polishing can, it can be made from household items.
Solid, lead-free solder is the second ingredient that can combine with silver polish to create a tinning solution. Soldering liquid is another thing that is not only essential to creating a tinning solution, but it is also crucial to designing printed circuit boards in and of themselves.
Create the skills needed for tin plating solutions
Create tin plating solutions, especially when using household items from scratch, will require some skills. A lot of “experts” in PCB related issues will foolishly say that it is easy to make not only tinning solution but printed circuit boards ultimately with household items.
It is possible, and these individuals are not wrong. However, making your printed circuit board and tinning solution does require specific skills and knowledge. Moreover, while these skills can be learned from tutorials, there is a significant risk to this.
The one skill that will make you a much longer way when it comes to creating a tinning solution, as well as other materials related to printed circuit boards, is introductory chemistry. The materials above and compounds are all compounds that require at least a basic understanding of the numbers and formulas that entail the discipline of chemistry.
It does not require a college degree to master introductory chemistry. Like with most DIY guides, a person can google their way to acquiring this kind of knowledge. Most of the materials mentioned in this have all the information needed to mix correctly, and it is possible to learn the basics of chemistry so that you can get started on creating your printed circuit boards and tinning solutions without needing any outside help.