What Is Reliability?
Reliability refers to “reliable” and “trustworthy” and refers to the ability of a product to complete a specified function under specified conditions and within a specified period. For end products, the higher the reliability, the higher the use guarantee.
PCB reliability refers to the ability of a “bare PCB board” to meet the production conditions of subsequent PCBA assembly and to maintain normal operating functions for a certain period under specific working environments and operating conditions.
How does reliability develop into a social focus?
Reliability originated in the “military industry” and later expanded to the “civil industry.”
In the 1950s, during the Korean War, 50% of the electronic equipment in the United States failed during storage, and 60% of the electronic equipment on board was unusable after it was shipped to the Far East. The United States found that unreliable electronic equipment affected the conduct of the war, and the average annual maintenance cost was twice the cost of equipment purchase.
In 1949, the American Society of Radio Engineers established the first reliability professional academic organization, the Reliability Technology Group. In December 1950, the United States established the “Special Committee on Reliability of Electronic Equipment,” and the military, weapons manufacturing companies, and academia began to intervene in reliability research, and in March 1952, they made far-reaching recommendations. The research results were first applied to the aerospace, military, electronics, and other military industries and then gradually expanded to the civilian industry.
In the 1960s, with the rapid development of the aerospace industry, reliability design and test methods were accepted and applied in avionics systems, and reliability engineering developed rapidly! In 1965, the United States issued the “Outline Requirements for Reliability of Systems and Equipment,” and reliability engineering activities were combined with traditional design, development, and production and achieved good benefits. ROHM Aviation Development Center has established a reliability analysis center engaged in the reliability research of electronic and electromechanical, mechanical parts, and electronic systems related to electronic equipment, including reliability prediction, reliability distribution, reliability test, reliability physics, reliability Sexual data collection, and analysis.
In the mid-1970s, the life cycle cost of U.S. defense weapon systems was prominent, and people realized that reliability engineering was an important tool to reduce living costs. And the test method was adopted, which led to the rapid development of failure research and analysis technology.
After the 1990s, reliability engineering developed from military enterprises to the civil electronic information industry, transportation, service, energy, and other industries and changed from a professional to a “general industry.” The ISO9001 quality management system includes reliability management as an essential part of the review, and the professional and technical standards related to reliability are incorporated into the quality management system documents, which become the management provisions of “what it says must be done.”
Today, reliability management has been widely accepted by all walks of life in society, and the business philosophy of enterprises has generally changed from the past “I want to pay attention to product reliability” to the current “I want to attach great importance to product reliability”!
Why is reliability getting more and more attention?
In 1986, the U.S. space shuttle Challenger exploded 76 seconds after takeoff, killing seven astronauts and losing $1.3 billion. The root cause of the accident was the failure of a seal!
According to official statistics, the compensation caused by PCBA reliability failure accounts for more than 90% of the external failure cost!
According to GE’s analysis, for continuous operation equipment such as energy, transportation, mining, communication, industrial control, and medical treatment, even if the reliability is increased by 1%, the cost will be increased by 10%. With the high reliability of PCBA, maintenance costs and downtime losses can be significantly reduced, and asset and life safety are more guaranteed!
Today, looking at the world, the competition between countries has evolved into the competition between enterprises and enterprises. Reliability engineering is the threshold for enterprises to carry out the global competition, and it is also the magic weapon for enterprises to stand out in the increasingly fierce market!
why should PCB reliability be taken seriously?
As a carrier of various electronic components and circuits of signal transmission hub, PCB determines the quality and reliability of electronic packaging. As electronic products increasingly miniaturization, lightweight, more functional, and lead-free and halogen-free, continue to promote environmental protection requirements, PCB industry is showing a “fine line, small hole, layer, thin plate, high frequency, high speed” development trend, will be higher and higher to the requirement of reliability.
High-reliability PCB can play a stable carrier role and realize the long-term and stable operation of PCBA, thereby ensuring the safety, stability, and service life of end products, and enterprises can enhance competitiveness, improve reputation, expand market share, and improve economic benefits.
How to evaluate whether the PCB has high reliability?
High reliability is a practical science that combines “engineering technology” and “management art.” Steady production of high-reliability PCBs requires the establishment of a set of “standardized, efficient, collaborative, and controllable” management procedures, requiring factories to comprehensively control “engineering design, production materials, manufacturing equipment, process technology, quality assurance facilities, production environment, Management system, team quality” and a series of influencing factors.
Therefore, evaluating whether the PCB has “high reliability” requires in-depth confirmation that the following control items of the factory have been fully controlled.
1. Prevention mechanism
1) engineering design: customer requirements identification, information management, automation, and professional skills. Design standards and specifications, based on the modified manufacturability factory system process capability; Job specification, process standardization, engineering production automation;
2) manufacturing process: systematism, systematic management of the whole process of each step of the process control target, operation process, and working standard;
3) QC management: standardize the quality control standard, perfect quality assurance system to assist the process in improving the quality;
2. Process management
1) Quality and product safety system: IATF16949, ISO9001, GJB9001, UL, CQC, RoHS;
2) Engineering design: DFM specifications such as stack structure, impedance, minimum line width, minimum spacing, minimum aperture, copper thickness, etc.; production process design, material selection, manufacturability document design, etc.;
3) Production materials: supplier review, material evaluation, raw material inspection, raw material storage, etc.;
4) Process technology: process capability, production parameters, use of liquid medicine, first FA, etc.;
5) Equipment and facilities: evaluation, daily inspection, progress test, predictive maintenance, preventive maintenance, periodic maintenance, etc.;
6) Operating environment: dust-free, constant temperature, constant humidity, illuminance, etc.;
7) Quality monitoring: incoming IQC, process IPQC, process IPQA, final inspection FQC, outgoing OQC, letter tolerance test, etc.;
8) Management team: operating norms, risk identification, problem analysis, strategy analysis, etc.;
3. Quality assurance inspection
1) Quality yield: real-time monitoring;
2) Quality reliability: real-time/periodic verification;
3) Quality consistency: real-time/on-demand inspection;
4) Average trouble-free usage time: regular/on-demand verification;
4. Test verification
1) Signal performance: impedance test, signal loss;
2) Heat resistance: thermal stress, Tg test, TMA test;
3) Interconnection performance: IST test, current resistance, thermal shock;
4) Mechanical properties: peel strength, pull-off strength, solder resistance hardness, adhesion;
5) Insulation performance: withstand voltage test, damp heat insulation resistance, CAF resistance test;
6) Welding performance: cleanliness test, weldability test;
7) Corrosion resistance: Solder resists, chemical resistance, gold finger porosity.