How a test flow can be build for a car electronic sunroof control

#1
Hello dear colleagues!
I'm new in reliability testing but I do research on this topic very often. Could you tell me something about how a test flow could be build for a car electronic? Are there any limitation for creating a test flow?
 

Marc

Retired Old Goat
Staff member
Admin
#2
Hello dear colleagues!
I'm new in reliability testing but I do research on this topic very often. Could you tell me something about how a test flow could be build for a car electronic? Are there any limitation for creating a test flow?
I assume you are asking about a functional test. A test flow would be specific to the electronic assembly and dependent upon the assembly function(s). I wouldn't think there would be any specific limitations, and functions tested would typically include aspects such as voltage overload protection (i.e.: Not confined to specific functions the assembly is designed to do).

What is/are the function(s) of the electronic assembly?
 
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#3
Hello! I wish you all a happy new year + health 100% :).
I'm talking about an automotive electronic board, placed inside the car, which controls the sunroof.
 

Marc

Retired Old Goat
Staff member
Admin
#4
Well, your assembly/controller has a specific number of functions dictated by the design. E.g.:
  • Open, a switch input function
  • Close, a switch input function
  • Stop, a switch input function
  • Auto-Open, a switch input function, and
  • Close Stop If Blocked (to stop it if resistance indicates something such as an arm or body is encountered when closing) - A safety function
  • NOTE: I haven't seen one, but I assume Auto-Close could be a function.
Much like a door window. Those are the primary design functional aspects. They are function design inputs.

I'll start with a couple disclaimers:
I am not an electrical engineer. In fact, I am electronic design stupid. I worked on a lot of high reliability electronics projects over the years, always from a functional quality position and from a physics aspect such as circuit board component layout, weights and resonant frequency of the board - E.g.: Finite Element Analysis of circuit boards. I did learn a fair amount of basic things such as circuit protections and such listening to the designers, but actually designing a circuit board, programming any chips is an Electrical Engineer function - WAY beyond my expertise.

OK - So, in addition to your functional tests (listed above) you will have to find out what electrical functional tests, such as voltage overload protection, there are to test. That is information the project electrical engineer/board designer will have to provide.

In my experience I always worked with a cross-functional team. When designing functional tests, we would get together and determine what to test and where in the manufacturing process any functional tests would be performed.

I don't remember there ever being any limitations on test flow (sequence), but I'm not sure what you mean by 'limitations'.
 
#5
I was thinking more on the environmental stress tests e.g. temperature steps, vibrations, shocks, humidity tests... and the way these tests should arranged in a test flow.
 

Marc

Retired Old Goat
Staff member
Admin
#6
OK - If you are referring to environmental testing, I wrote some test plans back in the 1980's mainly for DoD aerospace projects. I took the assembly or board or component requirements and listed them. Typically they were contract requirements based upon what environment the item would be used in. At the time the test plans I wrote were called Environmental Design Criteria test plans and they could be quite broad. For example:
  • Vibration - Transportation of the item
  • Vibration - Use environment
  • Thermal Cycling - Profiles defined by use and transportation and storage
  • Thermal Shock - Mainly for stressing electronic assemblies and their components (also see Environmental Stress Screening)
  • Shock - Mostly done on assemblies used in extreme environments
  • Humidity - Storage and use
  • Explosive Atmosphere - Use environment
  • Salt Spray - Storage and use
When I wrote those test plans I started by profiling the item starting from storage as stock to transportation to the customer. Then stock/storage at the customer's facility.
Questions I then had to answer, such as Where will it be used, such as in what environments. Aerospace or military communications equipment? Typically Explosive Atmosphere testing was one of the tests. Will the item be stored and/or used in tropical environments? Think Fungus testing and Salt Spray.

Most of the test parameters were taken from Mil-Std-810 and/or predicted use.

You get into some predictive stuff. For example the design of a vibration test profile or a temperature cycling profile. This contains some very old stuff from some EDCTPs I wrote in the 1980's:

Misc-Profiles.gif


However - In all of this, I had to justify, for example, vibration profiles and temperature cycling profiles. These are things I learned how to do from people and various conferences back then.

To move on - You make a list of all the tests you believe are necessary and any required by the contract, as many often were.

From there testing was scheduled. There was never a specific sequence. Any sequence typically depended upon whether the test houses were booked up or not. For example, testing at Wyle was usually a schedule breaker because they typically had a backup. Even in-house testing depended on how much the lab had scheduled.

BTW - Also see: Environmental Stress Screening (ESS) - Difference between MIL-HDBK-344 & 2164A - Short but you mention ESS.

Bottom line: You decide on what testing to do and when to do it. Technically there is not really a limit on what tests you decide to do, but costs will definitely keep them to the realistic minimum.

FWIW - I always had a timeline - These days I'd probably use project software, back then there wasn't really much in the way of tracking software. Always a lot of pressure from upper management - "When will this be finished?" for example. So, you'd send something to be tested at Wyle and... They schedule the test but end up actually doing the testing 3 weeks late.

So - If you have 10 test devices and 15 tests to do, you just have to decide which to do when. Sometimes it makes sense if you have limited test units, or simlyhave a mind for a sequence, you might take a device and do vibration first, then humidity with the prediction that vibration damage where technically if the test device passes, the vibration may open it up in a way humidity testing will reveal the damage.

I don't know if I'm helping or not. I hope so. I was doing that stuff 30 years ago...

Also see: Reliabilty, maintainability and dependability standards list and The History and Rationale of the MIL-STD-810 testing standard
 

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