PCB programming failure can be a costly mistake. A single issue in the board can cause the PCB to drop dead or become defective and easily corruptible because of the compromised quality assurance process.
Programming PCB board testing methods are an essential part of the manufacturing process. Any quality manufacturer can have a list of procedure for ensuring quality, and we have collected the most important ones here:
（Pictures generated by abstract PCB programming）
- 1.Types of PCB Testing Methods
- 2.Functional Testing
- 3.PCB Contamination Testing
- 4.Optical Microscopy/Scanning electron microscopes (SEM)
- 5.X-ray Inspection
- 6.Micro sectioning analysis
- 7.Fixtureless In-Circuit Test (FICT)/Flying Probe Test
- 8.Boundary Scan Testing
- 9.Design for Manufacturing (DFM)
- 10.Design for Assembly (DFA)
- 11.Design for Test (DFT)
1.Types of PCB Testing Methods
In-Circuit testing usually appears in more substantial and BGA. The test is within the expected range and will not make a lot of changes to the product. You must have the right pads for the PCB programming and the design in hand, or you cannot conduct this type of testing.
Caption: PCB testing in process for any programming errors
Flying Probe Testing
This type of testing is very cost-effective in comparison to ICT. We can use it to check if there is a short circuit on the board, resistance, capacitors, inductors, issues with the diode, opens, etc. Remember that the flying probe test must never have the power on.
Automated Optical Inspection (AOI)
This method used a 2D camera or a couple of 3D cameras to capture the circuit board's pictures. After that, the program analyzes these pictures and compares them against the schema.
If the PCB does not resemble the schema, it is flagged as an error and goes for manual testing. However, such tests may not cover 100% of the PCB. Therefore, we must combine with the previous technology to improve accuracy.
It is an intense process, where power is channeled through the board for straight from 2 to 7 days. The purpose of this type of testing is that they are used to detect any new issues on the board, and it can even cause some damage to the parts which are under inspection. We recommend using PCB board programming to solve undesirable areas.
An X-ray technician works with this method to detect any board issues by checking the soldering connections, barrels, and any internal traces. This type of testing is excellent for identifying problems in components that are not visible but requires experts.
Caption: X-ray inspection of Printed Circuit Board (PCB) for any possible error
Many customers prefer the functional testing, and the manufacturers use this technique to ensure that the PCB programming will indeed power up. The customers usually supply the parameters of the experiment, and manufacturers can then develop a customized test. It is time-consuming and not ideal for products that need quick processing. But this is a real test to check the longevity of the product.
The test jig checks for the sensor outputs with specialized hardware that amalgamates with the PCB. A more complicated way of conducting test jig would involve pogo pins or using servos, like a switch. They are a process of communicating with the PCB to ensure that it works properly.
The cycling time on programming is a valuable factor in determining issues in programming. The cycle time is better to be less than 10 seconds, so concurrent programming is a popular manufacturing choice. It reduces programming time but might bump up the cost.
The process of PCB manufacturing can create issues while the assembly is in progress. The problem can be eliminated or reduced, so there is no chance of failure. Manufacturers test pads and various components for the same. Another thing to check is often the welding process, which higher the possibility of creating an accurate solder joint.
（PCB testing with equipment）
3.PCB Contamination Testing
Unclean surfaces and chemical leakage can cause an issue with contamination. There are standardized methods of conduction testing that check for the efficiency of the board cleaning process and the level of stability to ensure there is no contamination later on.
4.Optical Microscopy/Scanning electron microscopes (SEM)
The usual optical microscopy has a 1000x magnification and cannot provide the required depth of field. Therefore, in many cases, SEM with a magnification of 5000x or 100,000x can use SEM, with a very high resolution, we can find any problems of semiconductor chip process failure.
People use this to determine if there is a defect on the board. This tool can inspect components on the PCB board, which have joints hidden from sight, or an assembly is placed in a boat and can not check regularly.
Technicians can test for any particles, issues with wire dressing, gaps in the closing of the lid, integrity of the substrate, bad quality soldering, etc.
6.Micro sectioning analysis
This type of testing is done in PCB programming to detect various types of failure related to the thermomechanical issues：
defects in the components
short circuits on the board
insufficiency in the soldering process which creates a defect in reflow
the material used for the programming and opens on the board
7.Fixtureless In-Circuit Test (FICT)/Flying Probe Test
It is a category of In-Circuit Test that works without the manual properties, which lowers the testing process's overall price. This testing process works by using a simple fixture to keep the board in place; meanwhile, test pins are moving and testing the points that are directed by the software program.
8.Boundary Scan Testing
When the circuits of a multi-layer PCB is concerned, quality testing is highly crucial. It has become the standard practice in recent times. This testing approach is known for being pretty well rounded. It can include many different applications, including conduction of tests at the system level, testing of memory, quick programming and CPU testing, and other functions. It is a problem for the system test that has been running in.
9.Design for Manufacturing (DFM)
Check the relevant parts in the DFM process to ensure that the PCB does not cause any problems when entering the assembly process. It can detect the following issues when the PCB board has copper very near to the edge. It can create short circuits when the board is powered up.
The second problem is when the pins and traces are close to each other without using a solder mask. It creates bridges in the middle of pins and later the board short circuits, causes chemical damage and other problems on the board.
The third problem is that copper pieces can be detached and float on the PCB layer, a huge defect in the design. It usually clusters in places where islands of copper exist between the islands; this creates trace issues.
Caption: PCB Testing during the manufacturing process
10.Design for Assembly (DFA)
Using the DFA to know which PCB design process needs to choose, it can happen efficiently and quickly when the product goes up for assembly. This process works by reducing the material's inputs, selecting components that are easy to acquire, and leaving adequate space between the components so the PCB design methods and markings for the component can be completely transparent.
Like the DFM process, the DFA process needs to implement the project to reduce production costs and time as soon as possible.
11.Design for Test (DFT)
DFT is a common reference for the type of design, which is ideal for making the testing process more stable and cheaper. The programming circuit board created to consider "test design" factors will be very easy to test and find problems. It creates an ideal scenario for the manufacturer to conduct the tests quickly. But the designer will need to know what the use of test methods at each step of the manufacturing process, so they can work with the DFT model.
The testing method you choose largely depends on the cost, design, and applicability of the product. But testing is an integral step of the PCB programming. It can end up saving you a lot of time and money and keep the production process from getting derailed due to bugs.
If you are trying to test the PCB process successfully, you need to choose the right PCB supplier; OurPCB will provide you with the best PCB manufacturing service; you can contact us immediately for more information.