PCB News - What is the purpose of electronic product testing?​

What is the purpose of electronic product testing?

Almost every new boss will come to ask this question once, why do our electronic products need to be tested on the board-side ICT (In-Circuit-Test) circuit? Can ICT be eliminated? Because a pair of Agilent3070 ICT test fixtures cost about NT450,000, which is equivalent to the price of a car; and a pair of TR518 simple MDA (Manufacturing Defect Analyzer) also costs about NT50,000. Therefore, circuit testing for circuit board assembly not only costs money but also time, so why are companies still doing it?

Before answering this question, it may be necessary to explain the test process of circuit board assembly. Generally, after the traditional circuit board is assembled by SMT, AOI (Auto Optical Inspection) is usually used to check the offset, short circuit, tombstone, and defect of the parts. Then the circuit test of ICT or MDA, and then the function test of FVT (Functial Verification Tester) to confirm the function of the circuit board is normal. Among them, ICT fixtures are the most expensive, and FVT takes the most time. AOI is not necessarily used by every company and has limited functions.

Here comes the question. Since there are so many methods to confirm the quality of circuit board assembly, can the more expensive ICT/MDA be eliminated? Isn't there AOI and FVT that can be used to confirm the quality of the circuit board?

This is because both AOI and FVT have serious blind spots, and there is no way to achieve 100% test coverage of the circuit board, so so many test methods are needed to achieve the largest test. Coverage rate (coverage rate).

But isn't FVT a full-function test? How can there be no way to achieve 100% test coverage?

This is because there are so-called by-pass circuits and parts that cannot be tested by FVT during the circuit board design. These bypass parts are not used during normal functional test operations and cannot show functions. Such as protection circuits to prevent excessive current. Furthermore, AOI and FVT cannot confirm whether the resistance and capacitance of the electronics, capacitors, inductors and other parts used on the circuit board are correct, and these can only be measured by ICT/MDA, which means that ICT/MDA so far There are also functions that cannot be replaced.

Let's talk about more exciting topics. Many bosses will look at circuit board testing from the concept of production efficiency or Lean Manufacturing, thinking that it has no output value, so why not directly change all the circuit board test items or processes from Remove all the production lines? Or make the product the best from the beginning, so that there is no need to test, right?

This concept is really good. I also applaud him, but it's just applause. If you are the principal, unless the quality problem after the product is shipped completely does not do your business, if you dare to take the test, just wait for the customer to complain, return the product, and then leave.

I can only say that the test is just buying insurance for our products. Just like you drive carefully, you dare to make sure that there will be no accidents when you drive out. Since it's an accident, sometimes it's not you who hit people, but people hit you, isn't it? Do you dare to make sure that your own products will not have defective products? Or can you guarantee that you will not be complained or returned if you sell defective products to customers? If you dare not, then don't want to remove the test!

What you can do is to measure how much insurance you buy for your own products, that is, how many tests you need to do to ensure the quality of your products. How many tests are reasonable?
I think this issue must depend on other products. If it is a product related to human life and safety (cars, airplanes, medical, military products should also be included in this category), no matter how much it costs, it should be 100%. % Test coverage, because you can't afford to lose your life.

The second is products related to financial transactions. It is recommended that you also try to achieve 100% test coverage, because you are afraid to confirm how much the customer’s financial transaction loss will be. This may be a bottomless pit. If the company loses it, it may not be lost. rise.

If it is a general consumer product, there should be room for bargaining, depending on whether you dare to gamble. Some companies may remove the ICT/MDA test.
If it is a cheap toy, there will probably only be FVT tests left! ipcb is a high-precision, high-quality PCB manufacturer, such as: isola 370hr PCB, high-frequency PCB, high-speed PCB, ic substrate, ic test board, impedance PCB, HDI PCB, Rigid-Flex PCB, buried blind PCB, advanced PCB, microwave PCB, telfon PCB and other ipcb are good at PCB manufacturing.