Tin plating can produce a whitish-gray color that is preferable when a dull or matte appearance is desired. It can also produce a shiny, metallic look when a bit more luster is preferred. Tin offers a decent level of conductivity, making tin plating useful in the manufacturing of various electronic components. Tin is also FDA approved for use in the food service industry.
If tin whiskers are a concern in your manufacturing environment, then you should strongly consider a tin-lead plating alloy. Unlike pure tin, as previously mentioned, tin-lead can be effective at preventing formation of whiskers, making it an excellent choice in the manufacturing of electronic components such as printed circuit boards, connectors and semiconductors. Because both metals feature a high hydrogen overvoltage, the deposition of a tin-lead alloy can be produced via strong acid solutions without the addition of complexing agents.
A great way to keep up with the latest tin plating developments is to sign up to receive free monthly emails from SPC. They contain lots of useful information about plating and the metal finishing industry in general.
Today, companies create most semiconductor chips using silicon plated with another material. This outer coating protects the semiconductor from outside elements and connects it to the outside world. These plating materials can be anything from tin to gold, and each has a unique set of traits with different effects on the finished product.
As discussed, plating is one of the last steps in the semiconductor manufacturing process, but holds an important role as protective shell and interactive layer between the semiconductor's internal circuits and the outside world.
Manufacturers often plate semiconductors using a process called electroplating. Also known as electrodeposition, this process deposits a thin layer of metal on the surface of a work piece referred to as the substrate. The basic process is as follows:
This general process describes most electroplating. However, semiconductor electroplating is much smaller in scale than the average electroplating processes. The chips in question are often less than an inch in diameter, and the circuits inside them consist of miniscule wires. Any errors, such as breakage or the addition of dust particles to the semiconductor, can result in a defective product. As a result, semiconductor electroplating involves a few extra precautions and considerations in order to ensure the quality of the finished product.
Semiconductor plating serves a number of functions, which directly affect the performance of the semiconductor as a whole. Different materials produce unique sets of features and benefits to the semiconductor, including the following:
The electroplating process itself multiplies these benefits, which improves corrosion resistance, enhances electrical conductivity, increases the solderability of the substrate and protects it against wear.
Each plating material has a specific set of properties that affect the performance of the semiconductor it plates. In order to help choose which metal is the best plating material for your semiconductors, here is a summary of each plating material and what it does for the semiconductor:
The electroplating of tin, also called "tinning", is a cost-effective alternative to plating with gold, silver or palladium. Unlike these materials, tin is abundant and cheap, although it's not as conductive as other materials. Additionally, tin has the disadvantage of forming sharp protrusions, called whiskers, which can damage any materials surrounding it. SPC has developed a way of avoiding this by using a tin-lead alloy. This alloy naturally reduces the occurrence of these protrusions, and does not require an undercoating, unlike tin. Tin and its various alloys are used in semiconductors for corrosion protection.
Recent concerns over the impact of heavy metals on the environment have led researchers to search for replacements to the lead soldering used to connect electrical components. In an effort to become lead-free, many companies are turning to pure tin, which has good adhesiveness, to solder. Tin can also eliminate the need for lead soldering when used as a plating material.
Most people are aware of copper's exceptional conductive properties, which is why copper plating for semiconductors is quite common. This soft metal is extremely valuable in electronics manufacturing, offering both electrical and thermal conductivity. While it's possible to use it by itself, copper often receives an additional metal coating to prevent corrosion and enhance the electrical properties of the other materials.
Another precious metal, silver is also used for plating. While less expensive than gold or platinum, silver still offers several important benefits, including thermal and electrical conductivity, corrosion resistance and compatibility with several other types of metals. Manufactures often use silver to provide a coating on more active copper parts, because of its low contact resistance and strong soldering characteristics.
Gold plating for semiconductors is very expensive, but highly valued. This coveted metal is highly conductive and heat resistant, and serves as an excellent barrier to corrosion. Most commonly, gold plating is applied on top of nickel, which acts as a corrosion inhibitor by preventing rust from penetrating pores in the surface of the gold layer. It also prevents the diffusion of other metals into the gold surface, causing it to tarnish. This tends to happen with zinc and copper.
Recent hikes in gold prices have led professionals to consider palladium and palladium-alloy plating as a cheaper alternative, saving up to 90% of plating costs. Additionally, palladium is less dense than gold, resulting in lighter finished products with the same coating thickness. Though previously scorned for its lesser performance compared to gold, palladium and its alloys are now a leading alternative in efforts to replace and reduce gold in the plating industry. It's now often found in electronic and semiconductor manufacturing.
Klein Plating Works (KPW) offers industrial tin-lead solder plating services in accordance to Mil-P-81728. KPW offers a variety of tin-lead plating options, including 60/40, 90/10, and 95/5 tin-lead contents. Our team of industrial platers will work with you to determine the best specs for your needs.
Solder (also known as tin-lead) is a deposit containing a mixture of tin and lead. Solder plating is used on wire and electrical contacts to protect the base metal from oxidizing, it enhances solderability, and provides corrosion protection. Solder plated metals are often used in the electronics industry when solderability is a must. Tin-lead plating also helps eliminate the problem of tin "whiskers". However, due to the lead, solder has toxic properties and has become regulated. Please keep in mind that tin-lead solder plating, by its nature, is non-RoHS compliant.
There are trade-offs to be considered with either finish, and the decision depends on your requirements and preferences. Parts finished with Bright tin provide a shiny, aesthetically pleasing surface finish. It also provides somewhat lower coefficient of friction for mating with other parts, boards and connectors as compared to Matte tin. For example, press-fit interconnects often use Bright tin plating to reduce the required insertion force which in turn can reduce damages of the plated through-hole in the printed circuit board (PCB). Conversely, Matte tin finish parts are better suited for solder reflow processes, and suffer less stress effects from elevated temperatures. Matte tin will also retain its original color under high temperatures, compared with Bright tin.
Latest packaging technologies such as FOWLP and FC-CSP require a variety of plating solutions for different structures. Pillars and solderbumps are used for interface interconnection and are hence crucial to enable heterogeneous integration.
We produce high purity chemistry according to the latest and most stringent semiconductor industry requirements. Our 1,500m manufacturing facility located near Berlin in Germany is equipped with highly automated manufacturing equipment and enclosed production environments to ensure efficient, safe, environmental friendly and reliable production.
The plating used in the surface processing of the electrodes on the outermost surface of IC chips includes processes such as electrolytic copper, electrolytic nickel, electrolytic tin-silver, electroless nickel, electroless palladium and electroless gold. This plating is one major driving force for the continuing evolution of semiconductors.
In the manufacturing of semiconductors and the fine detailed plating that it requires, it becomes necessary to consider the working environment. Plating work at the sites of semiconductor manufacturing must be performed inside a cleanroom.
I have explained how it is necessary in the manufacturing of semiconductors that we are careful about the working environment where the plating is performed. In the same way, it is also unacceptable for there to be any fine dust particles mixed into the plating solution itself. For this reason, when plating solution is used, it is necessary to filter it.
There was a time when it was said that filtering plating solution would cause the solution to separate so that it would become unusable. Nowadays, however, the filtering of plating solution is the norm when performing plating in this kind of manufacturing and precision filtering is performed for the plating on semiconductors.
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