Tube-era Tektronix instruments use ceramic strips with metallized grooves to hold components and wiring.
The production method is discussed in US Patent #3,121,020.
Tektronix warned that these strips should only be soldered with silver-bearing solder because
«Repeated soldering with ordinary solder may weaken the silver-to-ceramic bond.»
Early instruments often contained a small spool of solder inside the cabinet.
Today, some solder types containing silver, e.g. Sn62Pb36Ag2, are still available.
Competitors like Lavoie used less sensitive tin-plated steel inserts that can be soldered with ordinary solder.