In general, most components are only rated for 2 to 4 re-flow heating cycles before internal damage occurs. On some components the initial re-flow cycle brings the component into the rated tolerance, and for others the PCB forms a bimorph cantilever that physically fatigues the chip contacts/leads.
Production yields are only part of the Infant Mortality Phase of the bathtub curve.
Some components do get more stable with age if and only if left alone, but you can count those on one hand if you still have all your fingers. That is also a 3 hour pedantic conversation no one wants to have.
I am secretly a sentient turnip... =3
Be kind to yourself first, and maybe get outside for a walk. Best regards =3
Apart from the absolute temperature, chips have a recommended heating/cooling cycle, including heating/cooling rates. That suggests that differential expansion is a factor, which would likely be cumulative (more cycles = more likelihood of fatigue and damage).
The above is intuition, not the hard data you want.
I think what you are doing is a great idea (effectively demanufacturing). I'm hoping you can solve the practicalities, which as far as I can see are quality assurance and being able to guarantee a steady supply of components and a price point below new.
Any plans to retape the components so they can be put though a pick-and-place machine, or are you looking more towards manual rework? I can see that there is room for innovation in efficient ways to get components off boards at volume, as most component removal is in the form of manual rework.
curious—what specific failure modes or uncertainties would you want eliminated before you'd consider using recovered parts, even just in production?
As an engineer, I wouldn't use second hand components for prototyping. When prototyping you need to eliminate as much uncertainty as possible. I'd consider using second hand components in production, provided there is a cost advantage, supply is reliable and my production line includes a test that would pick up faulty components. Even then, I'd be monitoring failure rates and reverting to new components if elevated failure rates caused costs. There's an argument that (well handled) second hand components might even have a lower failure rate than new as they have been burned in.
I'm guessing this company is targeting specialsied repair rather than production. Sometimes complex parts are no longer manufactured and the only option is second hand (often at a premium price).