Simply put, a bare PCB refers to a printed circuit board without any through holes or electronic components. They are often referred to as bare PCBs and sometimes also called PCBs. The blank PCB board has only basic channels, patterns, metal coating and PCB substrate.
What is the use of bare PCB board?
The bare PCB is the skeleton of a traditional circuit board. It guides current and current through appropriate paths and is used in most computing electronic devices.
The simplicity of a blank PCB provides engineers and designers with enough freedom to add components as needed. This blank board provides flexibility and enables mass production.
This PCB board requires more design work than other wiring methods, but it can often be automated after assembly and manufacturing. This makes PCB boards the cheapest and most effective choice.
The bare board is only useful after adding components. The ultimate goal of a bare PCB is to become a complete circuit board. If matched with suitable components, it will have multiple uses.
However, this is not the only use of bare PCB boards. Blank PCB is the best stage to perform bare board testing in the circuit board manufacturing process. It is essential to prevent many problems that may occur in the future.
Why do bare board testing?
There are many reasons for testing bare boards. As a circuit board frame, PCB board failure after installation will cause many problems.
Although not common, the bare PCB may already have defects before adding components. The more common problems are over-etching, under-etching and holes. Even small defects can cause manufacturing failures.
Due to the increase in component density, the demand for multilayer PCB boards continues to increase, making bare board testing more important. After assembling a multilayer PCB, once a failure occurs, it is almost impossible to repair it.
If the bare PCB is the skeleton of the circuit board, the components are organs and muscles. Components can be very expensive and often critical, so in the long run, having a strong frame can prevent high-end components from wasting.
Types of bare board testing
How to know if the PCB is damaged?
This needs to be tested in two different ways: electrical and resistance.
The bare board test also considers the isolation and continuity of the electrical connection. The isolation test measures the connection between two separate connections, while the continuity test checks to ensure that there are no open points that might interfere with the current.
Although electrical testing is common, resistance testing is not uncommon. Some companies will use a combination of the two, instead of blindly using a single test.
Resistance testing sends current through a conductor to measure flow resistance. Longer or thinner connections will produce greater resistance than shorter or thicker connections.
Batch test
For products with a certain project scale, printed circuit board manufacturers will generally use fixed fixtures for testing, called “test racks.” This test uses spring-loaded pins to test every connection surface on the PCB.
The fixed fixture test is very efficient and can be completed in just a few seconds. The main disadvantage is the high cost and lack of flexibility. Different PCB designs require different fixtures and pins (suitable for mass production).
Prototype test
The flying probe test is generally used. Two robotic arms with rods use a software program to test the board connection.
Compared with the fixed fixture test, it takes longer time, but it is affordable and flexible. Testing different designs is as easy as uploading a new file.
Benefits of bare board testing
Bare board testing has many advantages, without major disadvantages. This step in the manufacturing process can avoid many problems. A small amount of early capital investment can save a lot of maintenance and replacement costs.
Bare board testing helps to find problems early in the manufacturing process. Finding the problem early means finding the root cause of the problem and being able to solve the problem at its root.
If the problem is discovered in the subsequent process, it will be difficult to find the root problem. Once the PCB board is covered by the components, it is impossible to determine what caused the problem. Early testing helps to troubleshoot the root cause.
Testing also simplifies the entire process. If problems are discovered and resolved during the prototype development phase, the subsequent production phases can proceed without hindrance.
Save project time through bare board testing
After knowing what a bare board is, and understanding the importance of bare board testing. You will find that even though the initial process of the project becomes quite slow due to testing, the time saved by bare board testing for the project is far more than the time it consumes. Knowing whether there are errors in the PCB can make subsequent troubleshooting easier.
The early stage is the most cost-effective period for bare board testing. If the assembled circuit board fails and you want to repair it on the spot, the loss cost may be hundreds of times higher.
Once the substrate has a problem, the possibility of its cracking will rise sharply. If expensive components have been soldered to the PCB, the loss will be further increased. Therefore, it is the worst to find the fault after the circuit board is assembled. Problems discovered during this period usually lead to the scrapping of the entire product.
With the efficiency improvement and accuracy provided by the test, it is worthwhile to conduct bare board testing in the early stages of manufacturing. After all, if the final circuit board fails, thousands of components may be wasted.