What is the lifetime of common parts/circuits these days ?

[tooki]

Any non soldered connection is prone to fail, though wire wrap is the best of the lot.

And soldered connections are also prone to failure. No type of connection is completely free of failures. And the types of failures they’re susceptible to differs.

I have had several vehicles where one of the control modules uses a pair of PWBs interconnected by square pins pressed into a heavily plated through hole.  I've seen the technique used in TE and some consumer products.  In the automotive application they often fail after a few years.  Soldering the pin into the hole resolves the issue.  Life is unknown, but so far substantially longer than the original method.

Press-fit connectors are widely used in automotive applications precisely because they have favorable performance characteristics in that operating environment. It’s certainly not done to save money, because as I understand it, it’s a more expensive process than soldering. It requires an extra process step that can’t be shared with other THT components, and it places MUCH higher demands on hole tolerances than THT soldering.

That you had multiple failures is either indicative that a particular auto manufacturer or its supplier have poor process control, or that you just had incredibly bad luck.

What you and I don’t know is how high the failure rate would have been if they had used soldered connectors from the start. It’s possible that the failure rate would be much higher. There is no chance the auto manufacturers haven’t done testing, as well as analysis of actual failures.

[tooki]

While I technically agree with you, any process which requires tight quality control for success is less robust than one which doesn't.

Well sure, but the more “robust” (I would say “tolerant” instead) process may not be capable of meeting the required performance standards. So we can only say that “more tolerant = better” with the qualifier of “all else held equal”.

[CatalinaWOW]

Press-fit connectors are widely used in automotive applications precisely because they have favorable performance characteristics in that operating environment. It’s certainly not done to save money, because as I understand it, it’s a more expensive process than soldering. It requires an extra process step that can’t be shared with other THT components, and it places MUCH higher demands on hole tolerances than THT soldering.

That you had multiple failures is either indicative that a particular auto manufacturer or its supplier have poor process control, or that you just had incredibly bad luck.

What you and I don’t know is how high the failure rate would have been if they had used soldered connectors from the start. It’s possible that the failure rate would be much higher. There is no chance the auto manufacturers haven’t done testing, as well as analysis of actual failures.

While I absolutely agree that the manufacturer did testing, I am equally sure that the testing was some form of HALT testing (highly accelerated life test) which predicted adequate results for their needs.  But their warranty on non-drive train components is a time or miles thing, both resulting on average in a warranty about half the observed failure time.  So it may not have been worse than intended process control, just my needs differ from the manufacturers.  Or it may have been a failure mode that their HALT process failed to accelerate.  These are 1999 vehicles, the failures occurred in the 2007 time frame, and I am only now finding that service and repair time and costs are rising to the point that I am disappearing the vehicles.  I had multiple copies because that years model turned out to be a perfect fit for my needs, better than any vehicle before or since.  Found I loved the first one and bought used ones about a decade later as good values appeared on the market.  Don't know what I will do when the remaining ones rot under me.  After substantially more than a million miles total service.

There are some other quirks about these vehicles that provide insight into keeping any kind of equipment going over long intervals.  I purchased a service manual for the model, which was new enough that all the actual service manuals are an on line subscription service from the manufacturer.  Someone had downloaded the then current version and got it to run stand alone.  Which was performed by having a virtual machine running in VMware that had Windows XP running is some sort of OS/2 warp shell.  Somewhere is the last couple of years an execution mode in VMware was deprecated and I no longer have access to the service manual.  I am sure with enough effort I could get access again, but that along with the increasing difficulty of finding parts for a 25 year old car and upholstery that is finally wearing enough to matter and frame rust that is starting to matter (and the aging and unwillingness of the operator to do heavy wrenching) it is just more effort than it is worth.

Automobiles are complex systems with many, many decay modes.  Most of our electronic devices are simpler and far more robust.  But the same general problems apply.  Not only does the device gradually fail with time, but the infrastructure to maintain it erodes also.