old ceramic ICs, ground trace on surface of package?

[Skaface]

I have a collection of old ceramic ICs, and have always wondered why they have a ground track on the surface of the chip running from the center of the package to the outer perimeter. I can only guess it was used for testing the package in the factory before it was released for sale? I have searched everywhere and haven't been able to find any information about this anywhere! I am sure someone here will know what this is for!

[T3sl4co1l]

I mean, the shielding is nice, and grounding what would otherwise be unconnected metal is responsible for ESD purposes for example.

Tim

[inse]

The ceramic substrate type with visible traces is especially nice

[BrokenYugo]

Trace is part of the ring of metal the lid solders too, probably made the gold plating step easier?

[Roehrenonkel]

Hi Skaface,
 
...is there a connection to any pin?

Best regards

[coppice]

I mean, the shielding is nice, and grounding what would otherwise be unconnected metal is responsible for ESD purposes for example.

Tim

That doesn't explain why they so commonly have a line from the lid to the end of the package, going to an area where nothing else appears to connect. I think someone told me the reason decades ago, but I can't remember what it was.

[mikeselectricstuff]

Might be for the gold electroplating process

[Benta]

It connects the lid to the lead frame which carries the die. Very good for shielding and ESD ruggedness.