What's inside an implantable Medtronics Itrel 3 Neurostimulator designed for Neuropathic pain reduction.
Dave tears into the ultrasonically welded titanium case.
Dave, nice tear down. Back in the '90s I worked for a pacemaker company and for pacemakers, the 2 clam shells are welded together in a helium environment with a laser welder, therefore the interior is sealed after welding with high helium content that also keeps things dry inside. The helium allowed the welding to occur without nitrogen yellowing of the titanium case, which, we ran tests in a highly nitrogen environment and discovered the yellowing effect after welding.
An interesting fact about titanium welding is that the "dust" that accumulates from the welding is very volatile when exposed to atmosphere (21% oxygen, 78% nitrogen, 1% other). The filters used in the welding cabinet would have to be pulled and immediately placed into a zip lock bag that had a shot of helium injected into it. The technician performing this maintenance would have to quickly carry the filters outside to the parking lot and pierce the bag in an open area and allow it to start fizzling and burning and would beat on it until satisfied that all of the dust had been exposed and the reaction was complete (had stopped burning) before tossing the filters into the dumpster.
We always watched this spectacle every month on the scheduled day to insure that the pyrogenic reaction was done before the filters were thrown in the dumpster.
Also, you are correct about the differences between this device and the pacemaker. The pacemaker hybrid is much more complex. In our hybrid assembly facility, which was a class 10,000 clean room, we manufactured everything onsite except for the ASICS. We received the wafers, however and sawed the chips off of the wafers and placed them into special containers that we developed. This was done outside of the assembly area in a special room. The saw had air bearings and turned at very high RPMs. This machine was very specialized and very precise.
The substrates were made onsite from green tape. These substrate boards had 9 layers and once the shape was cut from a "cookie cutter" from the pliable green tape form, then had all of the vias punched from a special machine that was developed specifically for this process. The vias were filled with a gold paste under very high pressures and the traces were done in a similar manner. Once all operations were done, the substrates would get baked in a very long oven which had a conveyor made from a chain like construction made from stainless steel.
I could go on and on about the different processes. My job was to study new machines that was purchased for specific operations/processes and to custom modify them to do specifically what we needed it to do. We also created and designed some of our machines, such as the laser welder mentioned above, when we could not find what we wanted on the market. As our processes matured, to revisit the machine and either modify to hone in on the design or make recommendations about future machine purchases. I had a blast with that dream job.
It all ended when the parent company decided to sell the pacemaker division to a rival company who only wanted our pacemaker leads, which were at the time, the best in the world. After the new company plundered that technology, all 1500 employees were laid off. This was in 1999, I started with the company in 1989, and was laid off on my 10th anniversary with the company.
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