PCB Tests & Inspections
To make sure the highest quality printed circuit boards to our customers, we will implement a lot of testings and inspections during our PCB production processes or after PCBs are finished. Here are the main tests & inspections we have done.
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IQC (Incoming Quality Inspection)
IQC (Incoming Quality Inspection) is a crucial process to ensure the quality of PCBs (Printed Circuit Boards). It is a complete inspection system aimed at finding any defects or inconsistencies in any of the material we used in PCB manufacturing. These material include CCL which is the most important one, copper, dry film, solder mask, silkscreen, and many more.
IQC should be undertaken with utmost attention to detail, as defective PCBs may lead to very high lost to both our customer and us. IQC can not only save on costs due to defect detection but also help maintain high levels of customer satisfaction by ensuring that products are built according to the highest standards. Therefore, IQC is essential for producing reliable and quality PCBs and should be noticed.
Manual Visual Inspection
Although AOI (Automated Optical Inspection) ,electrical test and other testing/inspections are used in our PCB manufacturing process, but manual visual inspection is still needed in a lot of places. Such as visual defects in base material, imperfection in solder mask, silkscreen etc. , since these minor defects cannot be defected by equipment. Manual Visual Inspection involves a meticulous visual examination of PCBs to detect any visual defects or flaws in the circuit boards before they are sent out for use.
This inspection gives us and our customers confidence that the product will perform according to IPC-A-600 Class 2 or 3 standards and customers’ standards. We ensure that our inspection process complies with the latest industry standards and best practices. So our inspection personnel have adequate training and experience and access to the required testing equipment.
Nowadays, advanced AVI (Automated Visual Inspection) machines are developed, but we think manual visual inspection is still needed.
AOI (Automated Optical Inspection)
AOI utilizes high-resolution cameras to capture images of PCBs at different angles, which are then compared to reference images to detect any defects or inconsistencies. Thus, manufacturers can quickly identify issues within their production lines without slowing production times or compromising quality control.
By leveraging AOI in PCB manufacturing processes, manufacturers can catch errors before they become costly problems down the line. It helps reduce waste and improves overall efficiency, as PCBs that would have passed inspection without AOI can be quickly identified and discarded. Manufacturers can keep up with their rigorous quality standards by using AOI technology in PCB production lines while ensuring a consistent end product.
In our PCB manufacturing processes, we mainly use AOI to check the minor defects in copper trace, such as copper trace voids. Besides, AOI is also used in solder mask process to detect the solder mask problem.
So, we think automated optical inspection (AOI) is an essential part of PCB manufacturing to ensure PCBs are free from defects and meet the highest quality standards.
FAI (First Article Inspection)
FAI is an essential tool for PCB manufacturers as it assures that their products will function as expected. It also allows them to identify issues early in manufacturing, preventing costly rework or scrap down the line.
In PCB production process, problem in any process may lead to scrap for whole batch production. So we need to make sure the PCBs are 100% meet customer’s standards and industry standards in the first. So before mass production, we will ran a few prototypes as first article, and check if the first article meet all the standards first.
By conducting an FAI, PCB manufacturers can also ensure that their PCBs meet industry standards such as IPC-A-600 acceptance standard. In addition, it guarantees that all PCBs produced by a PCB manufacturer are of the highest quality possible and meet customer requirements.
Micro-section inspection
Micro-section Inspection involves taking a small sample from each PCB and inspecting it under a microscope, looking for any defects or inconsistencies. By doing this, manufacturers can spot potential problems before they become costly issues during production or after installation.
We think the most critical element in PCBs is copper plating. Without proper copper plating thickness and conditions, PCBs will not functional well or not durable. In Viasion, we will implement 4 times of micro-section and inspections during our PCB manufacturing process, to check if the copper plating thickness is enough or not, and if there is any imperfections in copper plating. Besides inspection of copper plating, we will also inspect if the dielectric thickness is the same as the design, and if the solder mask thickness meed the IPC-A-600 acceptance standard.
Micro-section Inspection is an essential step in PCB manufacturing since it will have us to detect any hiding defects and guarantees the quality of the finished product. Beside, it is helpful to identify potential problems before they become costly issues in production or afterwards.
Electrical Test for Open/short
We all know that PCBs (Printed Circuit Boards) are essential components of many electronic devices, and PCBs’ performance and reliability largely depend on their electrical integrity. Therefore, electrical testing for open/short circuits is essential in PCB production to ensure that all PCBs meet the required specifications before being delivered to customers.
Electrical testing for open/short circuits can detect any defects or inconsistencies in PCB trace, which could lead to performance issues or safety hazards down the line. So electrical test is essential for PCB production and must be performed precisely to guarantee high-quality PCBs that fulfil all requirements.
Electrical testing requires the use of specialized testing machines or testing fixtures. The PCB must first be connected to the test machine, where a voltage will be applied and monitored for any current flow abnormalities. The test results should then be documented, as this information is invaluable for inspecting PCBs in the future.
Here in Viasion, we use 2 kinds of electrical test for open/short. The 1st one is flying probe testing which is suitable for prototypes, and the 2nd one is Bed-of-Nails Testing. Both the 2 testing methods have their pros and cons as following:
| Items | Flying Probe Testing | Bed-of-Nails Testing |
|---|---|---|
Test equipment cost | High | Medium |
Fixture needed | No | Yes |
Test speed | Low | High |
Reliability | High | High |
TDR Impedance test
With the improvement of the working speed of digital circuits, the transmission rate of signals on the PCB board is also getting higher and higher. For example, the signal rate of PCI-Express has reached 2.5Gb/s, the signal rate of SATA has reached 3Gb/s, and the working rate of new standards such as PCI-Express II, XAUI, and 10G Ethernet is higher. As the data rate increases, the rise time of the signal will be faster. When the signal with fast rising edge meets an impedance discontinuity on the circuit board, it will produce greater reflection. The reflection of these signals will change the shape of the signal, so the line impedance is a key factor affecting the signal integrity.
For high-speed circuit boards, it is very important to ensure the continuity of impedance on the signal transmission path, so as to avoid large reflection of the signal. Accordingly, for the test, it is also necessary to test the impedance change on the signal transmission path of the high-speed circuit board and analyze the cause of the problem, so as to better locate the problem. For example, PCI-Express and SATA standards need to measure the impedance of the transmission line.
To conduct impedance test, a fast and effective method is TDR (Time Domain Reflectometer) method.Its working principle is based on the transmission line theory, and its working mode is a bit like radar. As shown in the figure below, when a step pulse is added to the line under test, reflection will be generated at the impedance discontinuity point. If the source impedance (Z0) is known, according to the reflection coefficient (ρ)The impedance (ZL) of the measured point can be calculated.
With TDR Impedance Test, PCB manufacturers can ensure that their product meets all impedance requirements without going through lengthy trial-and-error processes. It provides fast, accurate measurements if impedance value and helps ensure quality PCBs that perform reliably in signal transmission. Using TDR Impedance Test, PCB manufacturers can save time, money and resources while guaranteeing their customers high-quality PCBs.
Solderability Test
Ultimately, PCB solderability testing is vital to ensuring the both SMD components and PTH components can be soldering on the PCBs without problem, no matter in waving SMD assembly by reflow oven or PTH assembly by waving soldering machine.
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Viasion Technology is your trusted partner & one-stop shop for PCB fabrication, components sourcing, PCB assembly and electronic manufacturing. With more than 16 years of experience, we have been supplying high-quality PCBs with competitive pricing for 1000+ customers worldwide. Our company is ISO9001:2015 Certified & UL Listed, and all our products are 100% E-tested and inspected by AOI & X-RAY to meet the highest industry standards. So please get an instant quote from our sales team now, and we will take care of the rest.