The PCB industry has advanced significantly in the recent millennium. OEM specifications and requirements have also advanced due to maturing technologies. With this, the requirements of electrical test of these higher technology products has advanced as well. Long gone are the pin-in-hole technology PCBs now surpassed by large multilayer, blind/buried, and rigid-flex technologies. For suppliers of electrical test, be it in-house or sub-contracted the industry specifications can be confusing, and at times non-comprehensible. OEMs direct the IPC specification (6012, 9252A, AS9100, etc.) for their fabrication to the manufacturer, but do OEMs and contract manufacturers (CMs) really understand what they are asking? Many variables are associated with these specifications and requirements to their designated classes regarding electrical test. OEMs decide what IPC class to which they wish their product manufactured due to performance requirements, but overlook the electrical requirements associated with those requirements. Manufacturing, plating, etching and all those processes may be within the class requirements they require, but they overlook the electrical requirements associated with their required IPC class. This paper will outline and define what requirements must be met for the OEM community to truly achieve the IPC class product from the electrical test standpoint. This will include the test point optimization matrix, isolation (shorts) parameters, and continuity (opens) parameters. This paper will also address IPC Class III/A additional requirements for aerospace and military avionics. The disconnect exists between OEMs understanding the requirements of their specific IPC class design versus the signature that will be presented from their design, resulting in many Class III builds failing at electrical test.
Minimum electrical test requirements are different between the IPC classes. This does not mean that opens or shorts are allowed! The electrical thresholds to identify these conditions are different. In the electrical test industry we are not only looking for the extreme cases (infinite open or direct short) we are also looking for indicators of what may be a potential problem. This is why the minimum requirements are different between classes (Table 1).
Ipc 6012 Class 3a Pdf
This is an exception beyond the standard Class III requirement for electrical test. In this case there are parameters specified when testing product under this class. These requirements need to be on the master drawing and communicated from the OEM to the manufacturer or this type of test may be overlooked. The differences with Class 3/A can be found in Table 2.
When manufacturing printed circuit boards (PCBs), the boards will be classified into specific groups based on the level of quality. Any circuit board developed for IPC Class III has met the strictest requirements levels based on tight minimum tolerances and very high precision standards for mission-critical PCBs that can be used in industries such as aerospace, military, and medical applications. Reaching these specific standards ensures that the PCB will endure a long lifecycle, can withstand up to harsh environments, and will perform at an exceptional level without failure.
Many manufacturers will also talk about their PCBs meeting MIL specifications. MIL spec refers to circuit boards that are built from scratch based on specific military specifications for the materials, design, layout, and fabrication of the board. The key difference between IPC Class III boards and MIL spec boards is that two different organizations govern and control the standards for each classification: The Institute of Printed Circuit Boards - Association of Connecting Electronics Institutes (IPC), and the Military Performance Specification Printed Circuit Board/Printed Wiring Board (MIL-PRF), along with International Traffic in Arms Regulations (ITAR). There will be specific stringent standards and inspections for each that need to be met.
The numbers for IPC and MIL Spec PCBs indicate the type of circuit board that the standards will apply to during its fabrication. The IPC-6012 refers to rigid circuit boards, IPC-6013 refers to flexible circuit boards, and IPC-6018 refers to high-frequency (microwave) circuit boards.
Foreign material represents the type of contaminated material and the amount of this material that may be present which will be accepted for that classification. The foreign material may come from the environment or be residual from the fabrication of the PCB.
The IPC (International Patent Classification) establishes the Strasbourg Agreement of 1971, and it provides a hierarchical system consisting of language-independent symbols. The application of IPC in high-tech industries is becoming more and more extensive. It is necessary to learn IPC class knowledge. This article seeks to unravel much to do with IPC Class; the meaning, category definition, and importance of IPC standard compliance.
With this article, rest assured of learning more than you thought you knew of IPC class products. In the end, you will comprehend IPC products based on the guide and distinguish categories 1, 2, or 3 of IPC Class PCBs to decide the type of products they need.
There are plenty of reasons why manufacturers Classify PCB products. Practically, the existing three class definitions, and some rigid codes, is all about the severity and number of allowable defects in a PCB.
Lastly, there are 3A-level cross-section standards. These are high-level cross-section standards, much higher than class 3 cross-section standards. They check for all aspects on the board in totality, not a single section, but everything.
The abbreviation IPC stands for International Patent Classification. It was established in 1971 under the Strasbourg Agreement. The PCB IPC standard uses language-independent symbols to provide a hierarchical system. Today, the majority of the high-tech companies in the industry are using IPC electronics. For one to effectively understand and use the IPC standards, they have to learn the different classes. We will look at the meaning, categorization, and significance of complying with IPC standards.
One must adhere to PCB when manufacturing electronics. Further, there are three fundamental categories that PCB electronics fall to. These categories define and show the different circuit board quality levels. They are class 1, class 2, and class 3. Class 1 is the lowest quality level, while class 3 is the highest quality level. All these classifications fall under the IPS-6011 standards. So we can define an IPC class as the PCB categorization standard used in electronics.
Various manufacturers apply these classifications to PCB products for different reasons. Some of the existing codes and the three classifications ensure adherence to the allowed number of defects and severity in a PCB product.
The lowest PCB quality level, class 1, has a significant acceptance rate of defective aspects. However, Class 3 PCB products have a very low tolerance to manufacturing defects. Circuit boards with multiple defects will not make it to the class 3 level. The stringent restriction on class 3 PCB products drives manufacturers to go above and beyond to ensure that their products meet the class 3 quality level if they want to remain relevant.
This Class exhibits higher characteristics compared to class 1 boards. Class 2 boards have an extended lifespan and are more reliable. To achieve this long lifespan and reliability, the products go through stringent standards in their manufacturing. Class 2 boards are not highly critical, and they run continuously. We find class 2 boards on devices such as tablets, communication equipment, laptops, and smartphones. 2ff7e9595c
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