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A quick look-up of the definition of breakthrough describes it as “a sudden, dramatic, and important discovery or development.” Breakthroughs are certainly dramatic and important. However, they are rarely sudden. Rather, they’re the result of years or even decades of incremental improvements, so much so that when they reach the tipping point they appear to have happened instantaneously. To think this about the new Low Temperature Solder process here would do a disservice to the dozens of Lenovo engineers who tirelessly searched for two years for a better way to manufacture PCs.

The problem and how to solve it gnawed at Tadashi Kosuga, senior engineering staff member and director of ECAT (Electronic Card Assembly and Test), for more than a decade. When lead-based solder was phased out from the industry and new environmental regulations like ROHS came into place in the early 2000s, Lenovo and other manufacturers switched to a tin-based solder process. While friendlier to the environment, the tin-based solder had some drawbacks: it required more heat during manufacturing, so it consumes energy while increasing the amount of heat in a plant and creating more carbon emissions. The high temperature also exposes the components in laptops and other devices to greater wear and tear, which could potentially affect reliability.

Reliability is a hallmark of ThinkPad laptops, and as Kosuga-san watched consumers demand thinner and lighter devices, he knew his team had to find a solution. This challenge had become personal. He approached his boss, Akira Fukushima, executive director of sub-system development center, and together they dedicated an incredible amount of time and put in place a cross-functional team of more than 20 engineers and resources to solve this nagging industry problem. The search began to find the recipe, or “secret sauce” for a low temperature solder process that could apply to all devices using printed circuit boards.

Tadashi Kosuga and Nobutuki Kamei, memory and component, ECAT and Components, Platform Subsystem Development, showing off a motherboard using the low temperature solder process. 

Finding the Secret Sauce

The recipe consists of only four ingredients – solder type, “flux,” (an additive to help flow of the solder), time in the oven and temperature. While this sounds simple, getting the proportion of each and combination of all of these factors right stumped some of the industry’s brightest minds for years.  For some engineering problems, our engineers could turn to complex mathematical models to help solve a design problem. However, in the world of solder and metallurgy, life is not that easy. Instead, they had to use classical experimentation and empirically observe, catalog and accept or reject each result. The team tried thousands of recipes, running experiments on more than 3,000 boards – each run of 30 boards took two to three weeks. The weeks added up to months.

Kosuga-san still remembers his disbelief the day around the six month mark where he thought they might be on to something. He determined that the solder joint using the LTS process met the same strength as the current process. Despite this discovery, he tempered his excitement. As an engineer with nearly 30 years of experience, he knew even though it was promising, the team would have many months of quality and durability testing and fine tuning to do.

Using surface mount technology (SMT), the solder and flux mixture is printed on the face of the circuit board. Then components are added and heat applied to melt the solder mixture, securing and connecting the components to the board used in the ThinkPad X1 Carbon 5thgeneration.

Just because they found a recipe that worked repeatedly didn’t mean that it would meet Lenovo’s rigorous testing standards. And even then, would it meet Kosuga-san’s expectation for excellence? A man of precision and exacting standards, he set the bar for the process at 2Xs Lenovo’s normal testing standards. The low temperature solder process had to create products that were flexible but that resisted changes in heat exposure. And remember, every product is different, so the process had to be a “one size fits all” approach.

The new process applies soldering heat at a max temp of 180 degrees Celcius from the previous of 250 degrees. By using existing materials for the solder paste and equipment, the new process doesn’t add cost. And with its lower temperature generating less heat, this process is already lowering carbon emissions; we’re using it on ThinkPad E Series, our largest volume commercial laptop, and on ThinkPad X1 Carbon, our premium commercial laptop.

Click here to see a breakout of potential carbon emissions saved in 2018.

But the story doesn’t end here. The typical course after discovering a new innovation is to seek patent protection for it. The team is pursuing this, but after investing so much of themselves in finding the solution, Kosuga-san and his team knew they needed to do more. They didn’t want to keep the new manufacturing process a secret. They wanted to do something uncommon in the industry – something different. They wanted to make the industry and world better by sharing their knowledge and solution. So after the patents are granted this year, they will proudly share this process technology via technical papers and consortiums with other electronics manufacturers  – partners and competitors alike. So even if you’re not using a Lenovo device, Lenovo engineering and innovation may likely be inside.