{"id":17866,"date":"2017-07-07T08:00:25","date_gmt":"2017-07-07T15:00:25","guid":{"rendered":"http:\/\/www.autodesk.com\/products\/eagle\/blog\/?p=1273"},"modified":"2023-09-25T13:14:47","modified_gmt":"2023-09-25T20:14:47","slug":"tin-whiskers-pcb-soldering-issue","status":"publish","type":"post","link":"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/tin-whiskers-pcb-soldering-issue\/","title":{"rendered":"Tin Whiskers: PCB Soldering Issue"},"content":{"rendered":"

What Are Tin Whiskers On a PCB, and How Can You Prevent Them?<\/span><\/h1>\n\n\n

Take a look inside all of your electronic devices, and you\u2019ll be hard pressed to find one that uses lead in its active components, switches, relays, and board finish. But it didn\u2019t always use to be this way. Before the enactment of the <\/span>Restriction of Hazardous Substances<\/span><\/a> (RoHS) directive in 2006, lead was being used in nearly all of our electronics. For good reasons, is was known for its ability to be a simple, inexpensive, and reliable way to create flexible solder joints that could withstand jolts and shock.<\/span><\/p>\n\n\n\n

The use of lead was how we were making circuits boards that would go into rockets, satellites, airplanes, and other high-performance applications that were bound to get jolted around during their normal operation. But this is the past now, and in the process of working towards a lead-free future for electronics, we\u2019ve run into a number of problems along the way, like tin whiskers. If you\u2019ve never had this problem plague your design, then cross your fingers, because it can happen at any time.<\/span><\/p>\n\n\n

What Are Tin Whiskers?<\/h2>\n\n\n

You might have overheard a fellow engineer talk about a tin whiskers issue, but talk is about all you\u2019ll likely get. Why\u2019s that? Because of tin whiskers, as much as they can plague our PCB designs and destroy them, are also almost invisible to the human eye, being up to 100 times thinner than a single strand of human hair in some instances. Check it out below.<\/span><\/p>\n\n\n\n

\"tiny-tin-whisker\"\/
See that tin whisker? Barely, but it might ruin this design. (Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n

Despite their almost invisible footprint, tin whiskers can create a bridge between the leads on electronic devices. And if you know anything about bridging, it\u2019s that a short circuit is close behind, ready to ruin your device. While the issue of tin whiskers isn\u2019t new, we had a relatively decent solution to them since the 1940s by using lead in our plating finishes and solder, but now we don\u2019t, and so the problem of tin whiskers has come back into the spotlight.<\/span><\/p>\n\n\n\n

The real issue with tin whiskers is that it\u2019s completely random when or if they will infiltrate your circuit board. We can\u2019t predict their patterns, and there are no quantitative data available that shows when a tin whisker might happen, it just does. So consider this – pure tin plating is used in nearly every electronic device around the world these days. We\u2019re talking about the electronics used for our communications systems, financial systems, transportation systems, power systems, and a whole lot more. What happens when a random tin whisker issue decides to crop up in one of these?<\/span><\/p>\n\n\n\n

You\u2019ll get a complete and total failure of a system that society relies on today to function, all because of a random issue that we have no solution. That\u2019s some scary stuff. This almost happened back in 2005, when the <\/span>Millstone nuclear power plant in Connecticut<\/span><\/a> experienced a random turn-off signal that would have shut down all of its operations. The cause? Tin whiskers.<\/span><\/p>\n\n\n

What Causes Tin Whiskers?<\/h2>\n\n\n

Here\u2019s the troubling part to stomach, we don\u2019t know exactly what causes tin whiskers. There are a ton of theories out there, but all we really do know is that when lead isn\u2019t used in electronics for plating and soldering, the risk for tin whiskers grows. A standard theory is that tin whiskers may occur when stress is exerted on the tin plating of an electronic device. Experts that agree with this theory have drilled down into the issue to spell out some factors that can cause stress on tin plating, such as:<\/span><\/p>\n\n\n\n