Constellation-based robotic visual servoing method for fault diagnosis of used printed circuit board assemblies

Experimental investigations have been performed to determine the heat transfer coefficients on both a horizontally and a vertically orientated simulated printed-circuit board (PCB) assembly in a laminar-flow region. The horizontal simulated PCB assembly consisted of two parallel horizontal plates, and the lower one was mounted with uniformly spaced, electrically heated rectangular ribs which were used to simulate the electronic components. The influences of Reynolds number, the ribs'pitch-to-height ratio (H / B), and the width-to-height ratio (L / B) on the convection from the PCB assembly to the ambient air were investigated. The horizontal PCB assembly was turned by 90° to become a vertical PCB assembly and similar investigations were performed. For both horizontal and vertical PCB assemblies, it was found that the variation of the ribs'heat transfer is strongly dependent on the Reynolds number, and the heat transfer coefficient for L / B = 4 is always greater than that for L /B= 3. This difference in thermal performance becomes larger with increase of Reynolds number. Comparing the heat transfer coefficients between the horizontal and vertical PCB assemblies reveals the fact that when L/B = 3,the horizontal orientation is better than its counterpart, but when L / B = 4, a similar result is obtained only for small values of H / B; for larger values of H / B, a converse result is obtained. Consulting two ribs of the same volume, the one with a larger top surface area has a better ability to enhance heat transfer. Correlations used to determine the heat transfer coefficient in terms of H / B, L / B, and Reynolds number were obtained from the experimental results.

PurposeThe generic design environment for a flexible printed‐circuit board assemblies (PCBA) remanufacturing cell contains four interrelated complex design domains. Mechanical design domains are really complex and the use of well‐proven mechanical product design methodologies does not help the designer. Hence, this paper aims to develop a generic systematic design methodology for a flexible PCBA remanufacturing cell.Design/methodology/approachThe study investigates the use of conventional mechanical product design techniques for the design of a flexible PCBA rework (remanufacturing) cell. It indicates problems and the weaknesses when conventional product design techniques are used for the development of flexible manufacturing systems (FMS). It then provides a new systematic mechanical design methodology for designing a flexible PCBA rework (remanufacturing) cell. The design methodology is intended to be generic in order to apply successfully to any FMS design.FindingsConventional product design methodology cannot be used directly for the design of a flexible PCBA remanufacturing cell. Hence, two design methodologies were developed: the generic FMS mechanical design methodology and a specific FMS design methodology for a PCBA rework cell. The first one was developed based on the tasks of the conventional product design process integrated with new design tools. The generic design methodology was then extended to obtain the second methodology for a PCBA rework cell design. Both of the methodologies were applied to a flexible PCBA rework cell design problem. Both design methodologies eliminated unusable design solutions at the early design stages of the conceptual design process and made the design process easier.Practical implicationsThe generic and specific design methodologies provide a better design environment, even for less specialized FMS designers.Originality/valueThe design methodologies may help for the commercialization of a flexible PCBA remanufacturing cell that may be used for SM rework and assembly.

Due to the proliferation of Information Technology (IT) equipment applications, including Artificial Intelligence (AI), Big Data, 5G, Internet of Things (IoT), Edge Computing and High Performance Computing (HPC) in recent years. Therefore, the hardware reliability of IT equipment is paid more attention in the industry. With the more and more severe environmental pollution, the air quality will also directly or indirectly influence the life of IT equipment wherever indoor and outdoor. In general, the hardware reliability of IT equipment was easily affected by corrosive gases, moisture, contaminants and particulate matter. It can potentially cause the electrical short failure due to creep corrosion occurrence on corrosion sensitive components, Print Circuit Board (PCB) and PCB Assembly (PCBA). Therefore, it is very important to verify the robustness against creep corrosion occurrence for the future electronics. Creep corrosion is a kinds of failure mode of sulfur corrosion, the typical feature of creep corrosion can be observed from PCB and leadframe packages. In environments high in sulfur-bearing gaseous contamination, the major corrosive product; cuprous sulfide (Cu 2 S) was formed due to the bare copper exposure. The solid corrosion products migrated over a surface of solder mask and molding compound without the influence of an electric field. Besides, the extent of creep corrosion may be so high as to electrically short circuit adjacent pads and traces, causing the electrics to malfunction which be known as the creep corrosion failure. Mixed Flowing-Gas (MFG) and Flower of Sulfur (FoS) were adopted widely for all suppliers in the industry. To consider that traditional testing method: MFG is expensive, long testing duration; and typical FoS testing of ASTM B809 standard is relatively inexpensive, short testing duration, but cannot verify the creep corrosion. In the light of the above, the International Electronics Manufacturing Initiative (iNEMI) has published a White Paper regarding the creep corrosion verification in August, 2018. The iNEMI project team, including the leading 3rd party testing lab for electronics verification: Integrated Service Technology (iST) and international branding system house: IBM, Lenovo, Nokia, Dow. etc. have analyzed the reason of creep corrosion occurrence and also developed a cost-effective and convenient testing method: iNEMI FoS test which is sufficiently well developed for consideration as an industry standard qualification test for creep corrosion To hope that iNEMI FoS test can assist the all suppliers to find out the prevention action and solution of creep corrosion failure occurrence in the industry. In this paper, we will present some case studies as well as solution cases by using iNEMI FoS test.

The trend to high-density packaging in surface mount assembly has highlighted inherent difficulties in the assembly line of these very fine pitch devices. A variety of defects is still common in printed circuit board assembly (PCBA) technology despite all the improvements made, and rework of PCBA is inevitable and performed manually in PCBA manufacturing floors since the cost of each component and PCB itself may be hundreds of dollars. In the last few years, the number of rework stations available on the market has grown considerably including the automated ones, but there has still been no significant reduction in the number of the defects. In electronics manufacturing, rework is defined as the activity that replaces defective components with those that are acceptable such that the populated board performs to the specifications. Increasing product complexity, decreasing component size, and using double sided boards have made rework more difficult and the economic reworking of PCBAs is one of the main problems facing PCB manufacturers. PCBA manufacturing has been relatively improved with fully automated, accurate assembly machines and the use of robots. Although significant improvement in automated rework has also been made by the author, it has been shown that the outcomes of the automated rework line have not produced a high enough level of the reliable yield percentage. The objective of this research project is to make a contribution towards this surface mount rework by creating a Computer Aided Process Planning (CAPP) system of circuit board defects so that the defects that necessitate rework operation can be detected through the electronics manufacturing assembly line. With the development of CAPP tool, the rework will be removed from the PCBA line and PCBA process parameters which cause joint level reliability problems will be troubleshot with the help of the developed system.

A printed circuit board assembly (PCBA) was failed, and two pins routed from CCGA had no signal output in the electrical performance test at low temperature (−25 ℃). Visual inspection, X-ray and 3D X-ray examinations did not find any failure in PCBA’s via/wire, solder joint, and CCGA body. In order to find the failure mode of the PCBA, more failure analysis is required. The commonly used vertical cross-section of PCBA will destroy the CCGA. This paper uses the method of cutting the CCGA columns in horizontal cross-section. After the cutting, microscopic inspection of the solder joints on both sides with the CCGA columns revealed no failure. The metallographic section of the solder joint on the side of the printed circuit board confirmed no failure. After the CCGA removed the columns, it is then re-balled and soldered to a new printed circuit board. The electrical performance test confirms that the fault is inside the CCGA. In this paper, the improvement of PCBA failure analysis solved the problem that CCGA will be damaged when cutting samples. The CCGA can be tested and chip-level failure physical analysis can be performed after the board-level failure analysis.

It is essential to understand that excessive strain usually results in various failure modes for printed circuit board assembly (PCBA) products. However, it is often difficult to measure the true strains of the critical component solder joints' connections on PCBAs directly. Based on analysis of the basic principle for strain gage test technology and strain-induced damage phenomena of PCBAs, this article studied on the application of strain measuring technology in reliability evaluation of PCBA under manufacturing process. Moreover, combining with an applicative example of strain measurement during mechanical assembly, systematic analysis was conducted on the strain gage selection technology for PCBA, specific operation method of strain gage tests during PCBA assembly process and strain data analysis method, in order to make further improvement on strain evaluation methodology in electronic industry.

Visual inspection has long been a necessary method of quality control in Printed Circuit Board Assemblies (PCBA) manufacturing. The characteristics of electronic assemblies have changed substantially over the last decade. Todays high lead count, fine pitch SMT components are becoming even more difficult for humans to inspect at the same time automated inspection systems have become reliable than manual inspection and are now accepted as valuable tools for producing high quality PCBA products. The basic requirements of an automated inspection system remain same in all PCBA manufacturing but the type of the automated system (off- line/on-line), where applied in the production flow, entire boards or only on a sample basis, inspection coverage (100% or partial) vary between different PCBA manufacturers. In PCBA manufacturing the emphasis is more in the electrical functionality of the PCBA than in it's appearance. It is nearly impossible to impose stringent specifications in the appearance of the components and other materials used in PCBA manufacturing. Due to the large number of component/PCB supplier and wide variations in materials and processes the challenge in successfully automating the inspection process is the variability in the appearance of components on PCBA. But in a high volume PCBA manufacturing where fewer board types are running in large volumes for long periods of time, the variability in component appearance can be controlled much better than a low volume PCBA manufacturing where more types are running in low volumes for short period of time. This paper discusses the development and implementation of a low cost flexible automated inspection system for PCBAs. The system can detect over ninety percent of visual defects on PCBAs. The key features of the system are quick and easy set-up, capability to inspect different types of board and quick change over between different boards and low cost.

It is well known that current engineering (CE) has shown its importance in the printed circuit board assembly (PCBA) testing phase. During the PCBA design process, the testing of PCBA quality must be simultaneously engaged with the manufacturing of the PCBA product, otherwise a defective PCBA product could be produced. This article presents a practical case of how to use an enhanced FMEA (called E-FMEA) system in the PCBA design phase to increase and ensure the quality of the PCBA product. The enhancement involves practical PCBA testing experience knowledge in the form of descriptive rules and their computerization using VBA (visual basic applications) macroinstructions in an Excel spreadsheet system. The creation of this enhancement is especially to meet the international customer requirements of the PCBA testing corporation in Taiwan. The proposed E-FMEA system is successfully applied in this studied large-scale PCBA testing corporation and greatly decreases the testing cost and shortens the testing time the customer requests.

Numerical and experimental investigation on heat transfer of multi-heat sources mounted on an array of printed circuit boards in a rectangular case

Testing and visual inspection of printed circuit boards (PCBs) and printed circuit board assemblies (PCBAs) are important procedures in the manufacturing process of electronic modules and devices related to locating and identifying possible defects and failures. Earlier defects detection leads to decreasing expenses, time and used resources to produce high quality electronics. In this paper an exploration and analysis about the current research regarding methods for PCB and PCBA testing, techniques for defects detection and vusial inspection is performed. The impact of machine and deep learning for testing and visual inspection procedures is also investigated. The used methodology comprises bibliometric approach and content analysis of papers, indexed in scientific database Scopus, considering the queries: “PCB and testing” and “PCB and testing”, “printed circuit board assembly and testing” and “PCBA and testing”, “PCB defect detection” and “PCBA defect detection”, “PCB and visual inspection”, and “PCBA and visual inspection”. The findings are presented in the form of a framework, which summarizes the contemporary landscape of methods for PCBs and PCBAs testing and visual inspection.

The vast majority of failures in electronic systems are due to thermal and vibration stresses. Major improvements in product reliability can be attained by validating the printed circuit board assembly (PCBA) design with respect to the thermal and vibration/shock environments in operation, manufacturing, and test. This PCBA design validation is accomplished with application-specific finite element analysis tools developed by Pacific Numerix Corporation, linked with common CAE/CAD tools in a PCBA level concurrent engineering (CE) system. Also included in this CE system is the capability to validate the PCBA design with respect to electromagnetic parasitics. Designs can be validated before the printed circuit board (PCB) is fabricated and assembled, resulting in a more reliable product, reduced quality costs and reduced product development cycle time. Communication inadequacies between various engineering disciplines and between engineering, manufacturing, and test is one of the major obstacles to concurrent engineering that is improved with this PCBA CE system. >

Purpose The purpose of this paper is to propose an effective and efficient solution method for the component allocation problem (CAP) in printed circuit board (PCB) assembly, in order to achieve high-throughput rates of the PCB assembly lines. Design/methodology/approach The investigated CAP is intertwined with the machine optimization problems for each machine in the line because the latter determine the process time of each machine. In order to solve the CAP, a solution method, which integrates a meta-heuristic (genetic algorithm) and a regression model is proposed. Findings It is found that the established regression model can estimate the process time of each machine accurately and efficiently. Experimental tests show that the proposed solution method can solve the CAP both effectively and efficiently. Research limitations/implications Although different regression models are required for different types of assembly machines, the proposed solution method can be adopted for solving the CAPs for assembly lines of any configuration, including a mixed-vendor assembly line. Practical implications The solution method can ensure a high-throughput rate of a PCB assembly line, and thus improve the production capacity without further investment on the expensive PCB assembly equipment. Originality/value The paper proposes an innovative solution method for the CAP in PCB assembly. The solution method integrates the meta-heuristic method and the regression method, which has not been studied in the literature.

In this paper, based on the printed circuit board(PCB) strain measurement technique, the relationship between the ultimate tolerance stress of a specific specification multi-layer ceramic capacitor (MLCC) and the PCB strain was studied by the bending test of the printed circuit board assembly(PCBA). In order to verify the correctness of the bending test conclusion, a new type PCBA was assembled, the simulation assembly test, environmental test were made for the PCBA and the metallographic analysis is made for the MLCC. The conclusions indicate that the strain of the PCBA around the MLCC less than 550ppm is a reliable boundary range.

Cost and performance analysis of a robotic rework cell

The process of manufacturing electronic printed circuit board assembly (PCBA) is a common process in technology companies. In particular, error checking of a PCBA with full components is a difficult job for human inspectors due to the high concentration and persistence. To solve this problem, many solutions have been studied, in which image processing technology has emerged as the best solution with advantages such as fast processing speed and high accuracy. However, the cost of these systems is often quite high for small and medium size companies. This paper presents a solution using image processing technology to check for missing components on complete PCBAs. Accordingly, a suitable algorithm is proposed for low-cost cameras, which allows building a simpler and more economical inspection process for both types of solder joints: through hole and surface mounting device (SMD). Consuming time to test a PCBA with nearly 50 components is less than 1 s. A cheap and easy-to-use Automatic Optical Inspection (AOI) system had been developed and used to test the actual PCBAs at the company.