IPC (Institute for Printed Circuits) is a global organization that creates documentation including electronic board design, printed circuit board manufacturing, quality control, soldering, wiring, testing, repair and reuse, and the standards it set forth are widely used globally and continuously improves quality standards. As for its history in brief… In 1957, some companies in the US came together and established an institute to create a welding and wiring standard. After 1980, trainings began to be provided as the know-how in electronic cards manufacturing increased to a certain level. IPC trainings have also started to spread in parallel to this. This training hierarchy is as follows: MITs (Master IPC Instructor), who are trained at the IPC institution, train CITs (Certified IPC Instructor) without any restrictions. People who receive CIT training can also provide CIS (Certified IPC Application Specialist) training. People who receive CIS training also ensure that IPC standards are applied in the field.
There are also authorized trainers in Türkiye, and CIT & CIS trainings are provided. The IPC institution has established a technical committee with the participation of members from various countries. The Committee creates a discussion environment every 4 years and updates its documents with new data from various companies. IPC documents are “alive” in this regard. Also, an exhibition called “IPC APEX EXPO” is organized every year for a comprehensive knowledge exchange. There are events with various organizations on a monthly basis. It is not mandatory to apply the IPC standards. However, due to its reliability, it is recognized by almost anyone in the world. It guides the manufacturers and customers by collecting and examining practical situations. It ensures healthy communication between the customer and supplier. By finding solutions to their problems at the design, production and quality stages, it enables them to meet at a common ground. We can call this a “common sense” for IPC. The IPC standards are also the basis for a quality business. IPC standards significantly reduce errors in processes. By assessing the processes with these documents, it increases the quality and reliability of the product. IPC standards in electronic board manufacturing are the standards consisting of rejection/acceptance criteria, and applied in order to improve the ability to make a differentiation. Now, let’s get to know the basic standards of IPC in electronic board manufacturing.
IPC-6012; Acceptability of Electronic Assemblies (Acceptability Criteria for Electronic Card Assemblies)
The last current series is IPC-6012D. The revision code changes with each update. This standard defines the qualification and performance requirements of rigid printing and flex printing circuit boards. It is a standard that guides the production and control of electronic boards. IPC focuses on customer’s actual request while meeting customer demand. These standards mainly cover quality assurance provisions including surface coating criteria, hole coating requirements, solder mask, top layer and in-hole coating requirements, board cutting standards, laminate requirements, marking standards, card curves, conductor requirements, pad structures, solderability, thermal tests and sampling frequencies, as well as verification during batch inspection. This standard is not independent and is binding with other IPC standards. To give an example… For the board outside cutting standards, the acceptance criteria for the notches formed on the edges of printed circuit boards, is that the measured distance from the edge to the nearest conductor should not be under 2.5 mm between the notch and the path. This design must be made in accordance with IPC’s another standard, IPC-2222 (Design Guideline Standard). When the margin is not designed in accordance with IPC-2222, the notches must be as agreed between the supplier and customer. If it is a substance that requires testing, the relevant IPC test document should be reviewed. IPC has specified the location of each relevant topic in the document with an item number. The description about the “board outside cutting” can easily be found from the Article 3.3.1 of IPC–6012D document, which is the last updated document. IPC also classifies products according to their complexity and performance in accordance with the intended purpose of use for the end user.
Class 1: General Electronic Products include the products with a limited-service life that are suitable for applications where the requirement is a function of the completed tool. The requirement is that the product should function smoothly.
Class 2: Intended Use Electronic Products include products where continuous performance and longevity are required, and uninterrupted service is desired but is not critical. We can give consumer electronics and white goods as examples.
Class 3: Electronic Products For High Performance/Harsh Environmental Conditions include products where continuous high performance is required, performance is critical, and downtime cannot be tolerated. We can give the medical, defense and automotive sectors as examples. Additional documents are provided for space applications. Performance requirements are specified separately in the document according to their classes. These classes specify the minimum acceptability requirements for printed circuit boards. They can also offer a higher performance. For instance, the minimum coating requirement for class 1 and 2 for the embedded pigeonhole is 20 um, and for class 3 it is 25 um. This coating value may be higher.
I PC-A-600; Acceptability of Printed Boards (Acceptability Criteria for Printed Circuit Boards)
The latest updated version is IPC-A-600J. We can call it a support document for IPC–6010, which contains recommendations containing shapes, images and photos that can help display acceptable/unsuitable conditions that may be observed from the outside or inside and is used for further understanding of existing requirements. This document is divided into “target”, “acceptable”, “unsuitable” and “process indicator” categories according to class 1-2-3 criteria. The target situation is close to optimal in many cases. However, although this is a “desirable” situation, it may not always be achieved and it may not be necessary to ensure the reliability of the printed circuit board in its specific working environment. Acceptable (not perfect) condition indicates the condition that will ensure the integrity and reliability of the printing circuit board in its specific working environment. The unsuitable situation is when the reliability of the printed circuit board in its end-use environment is not sufficient. For example, according to IPC-A-600, the existence of surface lines in the laminate is not the target surface line. What is acceptable is the proximity of the surface lines to the conductors in the laminate is not physically closer than 50% of the overall distance. If this limit is exceeded, then it is the “unacceptable” condition. The IPC-6012 and IPC-A-600 documents do not cover all of the reliability issues seen in the printed circuit industry. Therefore, the issues not specified in this document should be determined between the user and supplier. The auditor’s basic method of examination is to take a micro-section with visual control and machine equipment, and then examine it with a microscope. It is an assessment according to IPC standard documents and IPC standard test methods. IPC test methods are documented separately. The main purpose of IPC is to guarantee the manufacturing of the product according to the user’s request. It offers assurance to the customer by providing minimum requirements with the standardized data and test methods. It always gives priority to the purchase order of the end user. The supplier’s expectation from the customer is to communicate the demand for manufacturing clearly and in detail, in the supply document. If no specific instructions were given, usually the supplier should inform that the manufacturing will be carried out according to IPC 600 Class 2 Standard. The supplier and the customer should “trigger” each other for development. In order to achieve this, it is necessary to exchange information. Ozdisan Elektronik expands its know-how daily and shares its available information with its customers.
Source: Cengiz Oztunc’ IPC training notes, Elektronik Türkiye Journal notes
