PC Board Testing

Printed circuit boards are a crucial part of any electronic device and help in making devoice more valuable. Whether it’s a laptop, mobile, or a piece of complex machinery you can find a printed circuit board almost everywhere. Because this is responsible for the overall functionality of the device. If there are some issues with the printed circuit board then surely it will affect the functionality of the end product. The final product can have inconvenience and malfunctions. This will require more time and resources because the manufacturers have to recall the entire device again.

This is the key reason behind the motivation of testing a printed circuit board after designing. In other words, this practice is done to make sure that you are doing your work correctly. This gives the manufacturer assured that the final product would serve in the manner it is supposed to do. It is suggested that testing should be done in all the phases of the printed circuit board. Whether it’s a simple board or designed to handle complex devices. Now let us understand why testing is required for circuit boards.

Why is PCB testing required?

There is always an error in human-made things. No matter how attentive you are, there is always room for defects. And when you are designing some devices and technologies, the error rate is relatively high as compared to other developments. That’s the reason the testing phase of the printed circuit board is one of the most critical and complex stages that require more attention, time, and motivation. The testing phase is also recommended because many errors are overlooked in the designing and manufacturing stage. By testing your printed circuit board, you are making sure that your circuit is doing the same task.

The problems and failure rate can eventually be decreased with testing your PCB. It is also recommended that you should do testing with every phase of manufacturing. Whether it is designing or implementing a new idea, consider testing it. This will reduce the chance of failure and errors in the end product. It is difficult to resolve issues once a product is completed. That’s why most successful printed circuit board companies are working on a pre-planned testing procedure just to make sure that the end product is of high quality and free of errors. Moreover, testing also maintains customer satisfaction and enhances the chance of standing out from the market by delivering a high-quality product.

On the other hand, if testing is not done correctly or a circuit board is not tested then it may cause the company a huge loss of time and money. Revamping a product always costs more money and time. It is easy to control so many things such as tolerance, noise, general specifications, part by part variations, and other factors in the stage of PCB fabrication or PCB assembly. If the testing is done with every stage, then the integration or field failure rate can be lower in the early life cycle of product development. There are so many other things you can do in order to stand out on your printed circuit board. You can increase yields in the production stage, and you can confidently produce a printed circuit board that would be reliable and up to the mark.

Now you have understood that the testing phase is as much important as building the product itself. We have also discussed why testing is crucial at every stage of development rather than the end testing. Now is the time to view the testing methods and techniques used for printed circuit board testing. Because SMT assembly testing methods are an important part of the development cycle. All the renowned companies tend to offer a variety of testing methods so that users or manufacturers can select one according to the requirement. Here are the few methods that are used in printed circuit board testing:

Automated optical inspection method:

This method is also written as AOI. It can use both 2D cameras and 3D cameras for taking pictures of printed circuit boards. A detailed comparison with the schematic is then done after analyzing. If any board does not match the schematic, then surely there is a mistake in the manufacturing and designing part. The printed board is then sent to the technician for revamping purposes. AOI is also used to identify issues at early stages so that production can be stopped, and issues can be resolved as soon as possible. But AOI does not cover all aspects of the board. It does not power up the board so it’s difficult to provide 100% coverage to all the parts of the board. So, it is not a good choice to rely completely on AOI. Rather you should have a conjunction of AOI with some other tests. You can combine AOI with functional testing, incircle testing, and flying probe. All three offer the best combo to the AOI.

In-circuit testing method:

The in-circuit testing method or ICT is the most common and robust method available for circuit board testing. It is the most expensive method available. Tens and thousands of dollars are being spent on the fixation of size and other factors of the printed circuit board. Sometimes we call the ICT a bed of nails test. It actuates the circuitry of the printed board and is used to power up the board also. It is the best choice because it provides the maximum coverage of the board. It is designed in such a way that it can provide 100 percent coverage, but you will get coverage with a 19-15 percent decrease. This means in most cases it can cover 80-85 percent of the board. And this coverage will be free from human errors. A fixed probe laid out is used in this test in order to match the design of the circuit board.

It is given the name of the bed of nails test because the board is kept down on the bed to start testing. There are fixed points that are pre-designed on the board. These points allow the tester to connect the ICT test with the board. Connection is made with the circuit by passing a certain amount of pressure just to make sure that it stays intact. This test is recommended for ball grid areas and bigger connections.

You should go for this test if your product requires just a few revisions. But if you don’t have a pre-planned design for your circuit board distinguishing the pads on the board that you are going to manufacture then ICT is not a good choice and will not work for you. Also, you cannot select the ICT technique in the middle or end of the product because it does not allow that. If you want to use ICT testing, then you should consider pre-designing of your board first.

Burn-in testing method:

This is the most intense type of testing available for printed circuit boards. This test is designed in such a way that it can maintain load capacity and can identify early failures. As mentioned before this is the most intense testing so it may cause a destructive loss to the parts that are being tested. In this test, power is pushed in the circuit or electronic components with its maximum intensity. And the board is left with the power for 48 to 168 hours. Infant mortality occurs when the board is unable to bear this power. Infant mortality is suitable for certain industries such as medical or military. This is not recommended for every random project, but certain niches are there to which this testing suits the most.

This testing is a lifesaver and can protect you from embarrassment in front of customers or dangerous products before they launch.

Usually, pc board manufacturers don’t prefer burn-in testing because it is harmful to the board in some ways. It may put stress on the board more than it is rated for. But the stress can be removed after a certain period if few or no errors are found in the circuit board.

Flying probe testing method:

Okay, there comes the near to perfect method for testing your printed board. The flying probe is considered the best method available for testing and it is less costly than the in-circuit testing method. This is usually used when we want to do nonpower testing. This test identifies inductance, capacitance, shorts, resistance, opens, and diode issues. Although the ICT test makes it unnecessary for flying probe testing. But as we have discussed before, for implementing the ICT method, we have to design the board according to certain measures. On the other hand, there is no such restriction in the flying probe test case. It does not power up the board and is less costly at the initial stages of the testing.

There are so many other options at are available for PCB testing. Whatever method you are using you should check its requirements first. Also testing the circuit at every stage is compulsory because it reduces the matter of wrong product, and you can avoid rebuilding the entire product.

You get to know almost every method of Board testing. Interested in getting your Printed Circuit Board tested at affordable rates? PNCONLINE is your ultimate solution. Just write us now at sales@pnconline.com to get the job done.

Written by Sam Sangani

Sam Sangani is the President & CEO of PNC Inc., a Nutley, NJ based Printed Circuit Board manufacturer. Sam graduated from L. D. Engineering College with a BS Degree in Mechanical Engineering. He also continued his education and graduated from Steven’s Institute of Technology where he acquired a Master’s degree in Computer Science.

After completion of his BS, Sam worked as a QC Manager, for Xerox, Romania and London. He was responsible for the Quality Control of Cable and Wire Harness imports from Romania. After completing his Master’s Degree, he worked as a Senior Programmer with IBM, Tucson, Arizona. Sam was responsible for leading the Mainframe System Programming Team.

In 1997, Sam acquired PNC INC., a Nutley, NJ based PC Board fabrication Shop. From 1997-2013, Sam has made tremendous improvements and changes within PNC INC., as he added many new Products and Technologies in PNC’s portfolio. With his proven track record and leadership, PNC has never had an unprofitable year and has continued its growth yearly since 1997.

His current responsibilities are Strategic Planning, Corporate Management, New Business Ventures, Sales & Marketing, Trade Shows, Professional Services and leading productive teams to achieve peak potential. He has also utilized Lean Management techniques which have built a foundation for PNC’s high-paced growth. Sam also enjoys real-estate investing, web design & SEO, trading stocks, options, futures and Forex markets.