Alpha Assembly Solutions on Training, Education, and Low-Temperature Soldering

Estimated reading time: 17 minutes

Fullerton: I would probably say my design for manufacturing (DFM) class because it forced me to look at the world from a designer’s point of view, integrate how the designer views the assembly of a product, and identify opportunities for efficiencies to be gained by designing the part properly for the manufacturer. In my role, I am typically the recipient of that work from designers, especially when I'm working for OEMs and manufacturers. Many times, their biggest problems were caused by designers that weren't aware of how the choices they made at a design level impact the ability or inability of assembly of that part. At one of my jobs, I was infamous for taking boards on first prototype runs, walking them back to the design rooms, pointing out the things that were difficult for us that they caused, and showing them that there are other ways to solve the problems we encountered that could make my life easier—"We can all win in this.”

Holden: I haven't heard of too many DFM courses. How was that structured, and did they use Dewhurst and Boothroyd?

Fullerton: Yes, exactly. They taught us B&D DFMA. I still remember giving my final presentation on that luggage cart to Prof. Tuttle.

Holden: I never took a class like that, but that's one of my definitions of what design for manufacturing is—doing it right the first time and not design rule checking to find your errors. I’m glad to meet somebody that had a class like that in their education.

Matties: And considers it valuable.

Holden: Exactly—considers it one of the most valuable. It validates my opinion of that particular piece of knowledge. I never took a DFM class, but similar to that, the most valuable course I took was engineering statistics. It was not boring university statistics out of a book; instead, it included experiments on how to optimize black boxes. As a chemical engineer, they kept teaching me, "Don't worry what happens inside the box. Your job is to take A and B and make C for a profit." The big thing was to make a profit. “Let the scientists worry about what happens inside of the black box.” That was a design of experiments (DOE) approach, which is a form of DFM in a sense because your output is divided by input.

Fullerton: My second most important class was on probability and statistics, which was when I first realized I was in the right field of engineering. Calculus was hard and challenging, and I did well enough in it, but I didn't have to put much effort into my probability and statistics class, and I got an A because it came to me easily. Statistics and probability is the math of manufacturing. Calculus is the math of electrical and mechanical engineering, but randomness and variation in the world around us is the math you use in the manufacturing field. When I had such an easy time in that class, I confirmed that I had chosen the right path in my degree program.

Holden: I think I'll take this recording to my visit to Michigan Tech next week where they're putting together a PCB laboratory for undergraduates to get some hands-on experience.

Fullerton: Michigan Tech is an excellent school. The freshmen that are there will know what Kettering University is as well because it’s down in the under-the-bridge part of Michigan.

Matties: In addition to training and education, we recently published Alpha’s low-temperature soldering book. Tell me a little bit about the demands for low-temperature soldering and what people should know.

Fullerton: Low-temperature soldering has a number of significant advantages over standard tin-silver-copper (SnAgCu, or SAC) alloys and lead-free soldering temperatures, including the reduction in the stress on components and substrates on boards. Another benefit is the effect on warpage on thin substrates. Thus, the development of our newest material was driven by Intel and their need to develop thinner, larger, more powerful chips. The problem is that when we soldered them at 240°C at SAC temperatures, the warpage and integrity of the solder joint was a huge problem and head-in-pillow risks were much higher.

Thus, Intel approached us with this challenge and said, "How do we solve this through material development?" Our response was to look at lower soldering temperatures and low-temperature solders. The challenge of low-temperature soldering has always been that they are typically very high in bismuth. Bismuth tends to be brittle and doesn't stand up to the thermal cycling as well as Sn63 or SAC305 does. The challenge our metallurgists took on was to develop a tin-bismuth alloy that had low-temperature soldering properties but met or exceeded the reliability performance of the SAC305 solder joint in those system. Now, we have a successful customer that's currently using these in a low-temperature soldering system in a commercial product that’s in the field; people are using all the time, and they don't even realize it was formed with a low-temperature soldering process.

Matties: Is there a natural demand for this or is this something that people need to be educated on?

Fullerton: A little bit of both. Some challenges can't be met when we are soldering with the same SAC305 alloys; part warpage is a big one. There are other advantages that people can take advantage of, such as the reduction of the energy you consume or the elimination of wave solder by using a pin and paste on components that couldn't tolerate 240°C but could maybe tolerate reflow of 190°C. Suddenly, these parts are back in play and reducing an entire process out of your process flow is highly advantageous for operations.

Matties: Is there an approval process that OEMs would require or request to go through for this?

Fullerton: Typically, our strategy is to approach OEMs, especially if they are using EMS companies as their service provider because EMS companies do not have the authority to change something as significant as an alloy on their own. We have partnered with people like Intel and their customer, and we’re working with other OEMs to help them qualify this material at an OEM level; then, they can flow down the requirement as we take the material to their subcontractors.

Matties: What's the greatest challenge in convincing an OEM to go in this direction?

Fullerton: There is always a challenge to convince somebody to do something different. What I say a lot is that doing nothing is easy but doing something is hard. There is some effort required, and reliability testing needs to be done to gain the confidence in the performance of that alloy in the system to determine if it’s going to be what they expect when they need to deliver to the customer base. There is an investment in time, effort, materials, and money that occurs at the initial stage. There is also the challenge of convincing customers that the advantages down the road will be more than they are going to have to invest to get to that same level.

Matties: When OEMs look at the advantages, what do they most often hope for or what should they expect?

Fullerton: The reduction of defects, especially if you're using devices prone to head-in-pillow defects, is a big advantage. There are some benefits in the voiding realm too. Running a low-temperature process has inherent benefits when it comes to the formation of voids due to the flux, so there are some advantages there. Again, the reduction of the overall manufacturing cost is one that the EMS will achieve, and they can pass that on to their customers as a cost-save down the road or over time. These are benefits they can gain, but the trick is to quantify the benefits and make sure that the investment in achieving them has a payback with the benefits that you produce.

Matties: Is there a dedicated line at an EMS company that they have to install or how does this process integrate with a current flow?

Fullerton: Usually, there will be some offline prototyping that's done initially to do some general testing of the materials. Eventually, a robust and reliable engineering program will involve taking materials out of the standard manufacturing process and testing those as well to ensure that any variables that are encountered going from low-volume prototyping to high-volume production are considered when they run these tests.

Matties: One last question we always ask is what advice would you give to a young person entering this industry?

Fullerton: Get some hands-on as part of your education—don't just learn it out of the book. I've seen many engineers come out of college thinking they knew everything about everything because it was all in the book, and the day they entered the real world, they realized nobody uses their books anymore, so make sure you get some good real-world experience. Having a co-op helped me choose the right electives that I knew would support the areas I was interested in as well. I saw what the engineers used around me and then chose the classes to help me learn about the techniques and topics that they used.

Matties: Thank you so much for your time today, Jason.

Fullerton: Sure thing. Thanks for having me.

Visit I-007eBooks to download your copy of Alpha's micro eBook today:
The Printed Circuit Assembler’s Guide to… Low-Temperature Soldering 

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