Ceramic strips

Some Tektronix instruments use ceramic strips with metallized grooves to hold components and wiring. This started with the Type 315 in 1952. It continued into the early 7000-series instruments such as the 7514 mainframe and 7A18 vertical plug-in, both of which were introduced in 1971.

The production method is discussed in US Patent #3,121,020. The ceramic strips have turned out to be quite reliable. If they aren't abused, the only known failure mode is when they are used in HV supplies and are allowed to get very dirty. The dirt can become conductive, resulting in unintended current flow over the surface of the ceramic strip, and/or arcing. This can be avoided by keeping the HV circuit clean, particularly the nodes after the rectifier(s).

Tektronix warned that these strips should only be soldered with silver-bearing solder (3% AG was recommended) because

«Repeated soldering with ordinary solder may weaken the silver-to-ceramic bond.»

Early instruments often contained a small spool of suitable 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.

Links

• Tektronix video: Ceramic Strip Soldering Techniques
• US Patent 2,836,807, "Ceramic Terminal Mount"

Pictures

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  Silver Solder Spool inside a Tek 547 #1

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  Silver Solder Spool inside a Tek 547 #2