The Strategy Behind Identifying the Right Manufacturing Tests for Your Electronics
Bespoke Testing, Tailored To Your Needs
Like that hand-crafted, artisanal, hipster water you just ordered, a full suite of tests can be tailored to your particular design, budget and timeline needs.
As with all things in product design and manufacturing, there are tradeoffs to be made.
In my previous post I went through an overview of the most common manufacturing tests, now I will walk through two case-by-case examples:
Example 1: A Simple Board for Consumer Electronics
A good starting point is a generally simple PCBA for a consumer electronics device.
Maybe it’s for a toy; there are some switches, LEDs, a simple microcontroller, a speaker, but not too much else (no BGA parts in this example).
Let’s divide our testing needs up into what’s needed for when we’re first building the product (the NPI stage), and what’s needed for the long term Mass Production (MP) phase.
Early on you’re still validating the design.
In your first few runs through SMT, you’ll include an AOI step and a flying probe test.
Most solder joints are visible so there’s no need to X-Ray anything.
Flying probe is great to cover the ICT step without building an ICT fixture.
If the flying probe test reveals problem areas, you can build an ICT fixture for MP, but it may not be necessary.
And there’s a functional test, of course, to make sure your toy plays “Mary Had A Little Lamb” successfully.
You’ll put these first units through accelerated life testing and environmental stress testing for regulatory purposes, but that won’t be necessary in mass production.
By the time you’re ready for MP, that suite of tests is pared down to AOI and a functional test. Depending on your yield and cost to scrap or rework, you may even get rid of the AOI and simply do a functional test.
You’ll be losing a board to the occasional failure, but that may be cheaper than running an AOI on every board.
Example 2: Two Complex, Interconnected Boards, with Lots of BGA Parts
This is almost the exact opposite of the first example.
This product involves two PCBAs, with high-density interconnected, lots of parts that have high-pin counts and BGA pins, that is perhaps driving a bank of motors or other high-power systems.
And your aerospace client has a whole slew of regulatory and reliability requirements. It’s time for the full gamut of tests. You’ll probably be doing just about every test mentioned in this post, at least at first.
You may not need AXI in mass production, but you’ll definitely want it for your first build to check the complicated BGA connections.
A JTAG boundary scan may or may not be useful to you, but ICT is almost certainly required.
The reliability requirements mandate ongoing stress testing. And everything needs a hi-pot test to make sure it can drive all of those motors without failing catastrophically.
Depending on the regulatory requirements, you may be able to relax or remove some of these tests after your demonstrated high reliability and high yields, but you’ll still probably need AOI, ICT, functional testing and hi-pot testing on every unit coming off the line.
Test It In Production
I shouldn’t have to tell you how important testing is.
As you can see, it can also be pretty involved. I’ve barely scratched the surface.
However, I’ve covered the most common tests at a high level.
When it comes time to take your product into production, we can help you structure the suite of tests that is most suitable to your needs for reliability and cost.