If you’re taking a nonchalant approach in product testing, you risk having them failing in the field. It’s a fact observed from our experience and seasoned electronics engineers can allude to the bitter lessons.
An electronics product is made up of hundreds, or thousands of minuscule components. While a development prototype could work perfectly, you cannot assume that the production units will. There are many factors that come into play that could affect the product’s reliability and functionality.
For example, a communication IC’s transmit pin may lack adequate solder and it causes intermittent transmission loss. Such a problem is difficult to detect via visual inspection but manifests itself when the product is subjected to movement and vibration.
You’ll be getting a barrage of calls from frustrated customers and the technician will have difficulty locating the issue.
Some product issues are more obvious, such as a short between power and ground pads. Yet, you wouldn’t want the product to blow up in the field, which is why skipping testing is an inexcusable offense as far as electronics product development is concerned.
When Should You Test Your Products?
It’s a mistake to wait for the PCB to be fully assembled before you start testing. By then, it has gone through many processes which overcomplicate the test. Even if you’ve spotted an issue, it will be harder to identify the actual issue without removing some of the components.
So, when’s the best time to start testing your product?
You’ll want to start to do so when the PCB is being fabricated. It’s important that the PCB manufacturer runs a fixture test or flying probe test to ensure that each of the copper connections matches the netlist. The test also reveals any short circuits from thin strips of unetched copper.
Whether you’re engaging a Shenzhen PCB manufacturer or elsewhere, you’ll need to highlight that the PCB needs to be tested upon fabrication. If you’re fabricating in high volume, the fixture test is the more economical of the two.
The PCBs look complete and ready to go once the components are assembled. However, they are far from ready to be powered on, until some tests have been done. Ideally, you’ll want to have the automatic optical inspection done on every piece of the assembled product.
Rather than relying on human inspection, the PCBs are placed in an optical inspection machine, where they are scanned for anomalies like dry joints, short circuits, and insufficient solder. This is particularly important when you’re using component packages like BGA, where the solder lead is hidden from plain sight.
How Should You Test?
While machines take care of post-fabrication and post-assembly testing, you’ll be in charge of functionality and burn-in tests.
By now, you’ll have confirmed that the PCBs are free from manufacturing errors. Still, there’s the question of whether there are any issues with the components. Even if you’re purchasing from a reliable electronics components supplier in Shenzhen, there’s still a chance that a few of them may have issues.
You don’t want a single voltage regulator to land you into trouble with the customer. Or send out a PCB where the microcontroller has a failed PWM module.
Therefore, it’s important to run a functionality test on each of the PCBs to ensure that they are behaving according to the specifications. You’ll need to build test cases with pre-conditions and the expected results for each functionality.
Even if the PCB passes the functionality test, don’t be hasty to ship them out. There are some problems that materialize only after a period of time. While it’s not practical to test the PCBs indefinitely, it certainly helps to power up the PCB and let them run for 24 hours.
Performing the burn-in test gives you the confidence that the product is unlikely to fail within a short period after it’s been powered on.
What Should You Pay Attention To
These are the common modules where you need to focus on to ensure they behave reliably in the field.
Power Delivery Network
Every electronics product has a power delivery network. You’ll need to ensure that the operating voltage on the supply traces is at their respective value. If a component is internally shorted, you’ll find that the voltage is brought down drastically accompanied by an acrid smell from the burnt components.
If you’re working with power-consuming components like power MOSFET or arrays of super bright LEDs, you need to ensure that the voltage reading remains consistent even when the product is operating at its max power.
In an embedded system, the microcontroller is the core of the circuit. Every module of the microcontroller needs to be functional for the product to work.
During the functionality test, it’s best to have a simple test firmware that allows the technicians to quickly test out the I/Os, communications, memory, and other peripherals to ensure they are working accordingly.
Also, ensure that the crystal that drives the microcontroller is oscillating at the right frequency. Else, it will disrupt the microcontroller’s timers and code executions.
I/O and Visual Interface
Most electronics products have I/O modules on the PCB. They can be in the form of optocouplers, signal relays, MOSFET, multiplexer ICs, or related components. Regardless of how the I/O circuitry is built, you’ll need to test each of them to ensure signal integrity and continuity.
For example, a non-activated input of the optocoupler results in a logic 1 (+3.3V) on the output. You need to activate the input and ensure that the output drops to a logic 0 (0V). If the optocoupler is faulty, the output may dangle in the range of ~+2V, which will compromise the product’s functionality.
Some PCBs have visual indicators like LCD or LED built on it. Well, you need to ensure that they work during testing or it’ll defeat the purpose of integrating the visual components.
How To Increase Testing Efficiency?
Now, testing is a tedious process that contributes to the product’s cost. It gets more complicated when you’re producing a complex electronics product.
You need to be strategic when planning product testing. For a start, you need to have step-by-step instruction that details how the test is to be carried out. Make it simple for technicians to understand as they are the ones who will be carrying out the mass testing.
If you’re manufacturing in thousands, it’s more practical to develop an automated test jig. Rather than manually configuring each test case, the test jig automatically runs the test with minimum intervention from the technicians. It dramatically shortens the testing duration.
Also, you can improve testing efficiency by making some optimization during the PCB design stage. For example, you’ll want to insert the appropriate test points for critical signals and supply traces. It’s more efficient and less risky than probing on the component’s pad.
You’ll also run into less trouble with testing if you’re using a reliable electronic component supplier to start with. Talk to us and find out how you can achieve minimum product defects with high-quality components.