Test bench accessible even for your small production runs: Discover our affordable 'maker' approach

Introduction

Misconception: A test bench is only for mass production!

Ah, the joys of electronics manufacturing! We all love technology and are thrilled to receive a fresh batch of PCBs for a project. But let's be honest: when you have to spend hours manually flashing and testing each one, the excitement quickly fades into tedious repetition.

That’s when you start 💭dreaming💭 of automation and optimization… 🤓 A test bench 🤓!

People often think test benches are reserved for huge volumes, but the reality is quite different. In a team of makers, we love a challenge!

The Daily Challenge: Efficiently testing components, soldering, and functionality.

Many of us have been there: staring at a pile of electronic boards, ready to be flashed and tested before going into the final product. It is imperative to test them fully to avoid nasty surprises down the line.

Why a Custom Test Bench?

Automate the process, optimize your time.

Manual testing steps can quickly become monotonous. You might start out optimistic and motivated, but stop and really think about it for a second.

Before even powering the board, you have to check for potential short circuits:

• You grab the multimeter and position the probes on the test points. The board is wobbly, so it’s a struggle.

Once powered, you measure voltage levels:

• You fire up the lab power supply and, once again, hunt for the test points, hoping to see 3.3V and 12V on the multimeter.

Doing this by hand, over and over, is exhausting and prone to error. Quick, we need a test bench!! We have to automate all of this!

Then comes programming:

• You wiggle the mouse to wake up the PC, plug in the programmer (if there’s a connector), or manually hold the programming cable against the board while the firmware downloads. Then you wait to see "Success" in the logs. Patience…

Finally, verifying general functionality:

• Every project is different. It could mean plugging in a motor, verifying an NFC reading, checking a BLE connection to a smartphone, testing audio output, etc.

The Magic of the "Maker" Process

Identifying Needs Let’s analyze the board destined for flashing and testing. First, we identify the test points. Then, we list every function we can verify. This forms the foundation for designing the appropriate test bench.

This is also the moment to evaluate technical resources and decide what must be automated versus what can remain the operator's responsibility. For example: we could have integrated a small servo motor to physically press a button for testing. However, for budgetary reasons, we decided to let the operator press it. Since their presence is already required to visually confirm an LED lighting up, this made sense. If the budget had allowed, we could have developed a system using a photodiode to detect the LED light automatically. It is essential to define needs precisely and adapt the technical solution to the allocated budget.

Technical Design The heart of a maker lies in the art of mobilizing existing resources and recombining them. Inside a bench, you might find a Raspberry Pi, a USB barcode scanner, a USB NFC reader, and a Segger probe. However, there is one component we custom design: the PCB that houses the Pogo pins. These spring-loaded pins establish contact with the test points on the board being examined. for parts not available on the electronics market, we create them using modern tools like 3D printing, laser cutting, or CNC machining.

Assembly and Fine-tuning At BLUEGRioT, we are convinced that design is as much about aesthetics as it is about functionality. The chassis of the BLUEGRioT test bench combines innovation and efficiency; it was designed to be modular and accommodate a variety of components.

Use Case: Test Bench Example

A Deeper Dive: Details on a Test Bench After the general explanation, let’s look at a concrete example. We prepared a video that perfectly illustrates the process and the real time savings gained.

Proof by Image: The Comparative Video — Lucas Vs. Mehdi

1. The Protagonists: "On the left is Lucas, the operator enjoying the test bench. On the right is Mehdi, the operator equipped with his lab power supply, multimeter, and computer."
2. Traceability Management: "In addition to running tests, both operators must manage traceability. Lucas simply 'beeps' a QR-Code like a cashier. Mehdi, however, has to manually type the board's serial number and hardware version into a file, then tick 'pass' or 'fail' for every single test to track potential non-conformities."
3. Risk of Error: "For Mehdi, every step and every test is an opportunity for a mistake, an oversight, or a typo. Without a test bench, the process is not only tedious, but it also exposes the project to increased risk."
4. Competitive Spirit vs. Demonstration: "You'll notice Mehdi is in competitive mode, trying to go as fast and efficiently as possible. Lucas, confident he has already won, performs the 4 required gestures with disconcerting slowness, demonstrating the ease of the process like the hare taunting the tortoise."
5. Time Comparison: "Result of the test: 1'36" to run the test plan with the bench, vs 3'46" for the operator without one."
6. Optimization: "The most striking part is that the operator with the test bench (Lucas) has almost nothing to do. He basically just breathes slowly and stares into space. He could easily parallelize tasks—why not work with 2 or 3 test benches simultaneously to optimize further?"

How much does a custom test bench cost?

BLUEGRioT has built flashing and measurement test benches ranging from €6,000 to €60,000. Finding the sweet spot is crucial. You have to weigh the cost against the potential benefit.

If you commit €10,000 to a test bench for a production run of 500 boards at €25 each, the investment might seem unprofitable if you base it solely on saving money on scrapped/defective units.

However, it is vital to consider other factors, such as:

• Reduction in testing time (and therefore labor costs).
• Improvement in quality perceived by customers due to fewer failures.
• The ability to reuse the bench for other products or future versions.
• Reduction of indirect costs linked to human error and customer returns.

This is why we stand by our claim: The test bench is not reserved just for large series! Take, for example, our very recent production of 250 boards for the Reyouzz project!

Update: 10/04/2024

After receiving our new Raspberry Pi 5s, we couldn't resist the urge to test them on our bench. Without changing our usual settings, we launched our tests on this new hardware.

The results? Performance quadrupled, without compromising precision or time optimization.

Faster and stronger, the Pi 5 is a real boost for our custom tests. With reduced processing times and increased efficiency, we are better equipped than ever to bring our/your most ambitious ideas to life—and do it faster, thanks to the test bench.