Technical Library | 2008-02-20 21:42:52.0
Tier 2 and Tier 3 EMS companies face increasing pressure from competition in low-cost manufacturing countries to produce assembled boards at lower cost, with increased complexity and to tighter deadlines. They also face an increasing amount of high-mix, small-to-mediumvolume production runs. Even OEMs find it hard to predict what products they will be manufacturing in three to five years time, driving the need to invest in highly flexible production tools that will cater to their needs over the lifetime of the equipment. This paper examines methodologies for optimising the process, improving stock control and providing greater traceability using lean manufacturing techniques.
Technical Library | 2012-11-21 18:57:58.0
The continuing evolution toward advanced miniature packaging has led to ever increasing PCB density and complexity. As the manufacturing process becomes progressively more complicated, there is an ever increasing probability for defects to occur on finished PCB assemblies. For years the Automated Optical Inspection (AOI) industry has relied solely upon two-dimensional (2D) inspection principles to test the quality of workmanship on electronic assemblies. While advancements in conventional 2D optical inspection have made this technology suitable for detecting such defects as missing components, wrong components, proper component orientation, insufficient solder, and solder bridges; there is an inherent limitation in the ability to inspect for co-planarity of ultra-miniature chips, leaded device, BGA and LED packages.
Technical Library | 1999-08-27 09:18:58.0
A need to move beyond aerosol sprays and dipping leads to a development that answers tough requirements for controlled coverage, low waste, and environmental restrictions.
Technical Library | 2012-12-17 22:05:22.0
Package on Package (PoP) has become a relatively common component being used in mobile electronics as it allows for saving space in the board layout due to the 3D package layout. To insure device reliability through drop tests and thermal cycling as well as for protecting proprietary programming of the device either one or both interconnect layers are typically underfilled. When underfill is applied to a PoP, or any component for that matter, there is a requirement that the board layout is such that there is room for an underfill reservoir so that the underfill material does not come in contact with surrounding components. The preferred method to dispensing the underfill material is through a jetting process that minimizes the wet out area of the fluid reservoir compared to traditional needle dispensing. To further minimize the wet out area multiple passes are used so that the material required to underfill the component is not dispensed at once requiring a greater wet out area. Dispensing the underfill material in multiple passes is an effective way to reduce the wet out area and decrease the distance that surrounding components can be placed, however, this comes with a process compromise of additional processing time in the underfill dispenser. The purpose of this paper is to provide insight to the inverse relationship that exists between the wet out area of the underfill reservoir and the production time for the underfill process.
Technical Library | 2020-11-04 17:49:45.0
OEMs and CMs designing and building electronic assemblies for high reliability applications are typically faced with a decision to clean or not to clean the assembly. If ionic residues remain on the substrate surface, potential failure mechanisms, including dendritic growth by electrochemical migration reaction and leakage current, may result. These failures have been well documented. If a decision to clean substrates is made, there are numerous cleaning process options available. For defluxing applications, the most common systems are spray-in-air, employing either batch or inline cleaning equipment and an engineered aqueous based cleaning agent. Regardless of the type of cleaning process adopted, effective cleaning of post solder residue requires chemical, thermal and mechanical energies. The chemical energy is derived from the engineered cleaning agent; the thermal energy from the increased temperature of the cleaning agent, and the mechanical energy from the pump system employed within the cleaning equipment. The pump system, which includes spray pressure, spray bar configuration and nozzle selection, is optimized for the specific process to create an efficient cleaning system. As board density has increased and component standoff heights have decreased, cleaning processes are steadily challenged. Over time, cleaning agent formulations have advanced to match new solder paste developments, spray system configurations have improved, and wash temperatures (thermal energy) have been limited to a maximum of 160ºF. In most cases, this is due to thermal limitations of the materials used to build the polymer-based cleaning equipment. Building equipment out of stainless steel is an option, but one that may be cost prohibitive. Given the maximum allowable wash temperature, difficult cleaning applications are met by increasing the wash exposure time; including reducing the conveyor speed of inline cleaners or extending wash time in batch cleaners. Although this yields effective cleaning results, process productivity may be compromised. However, high temperature resistant polymer materials, capable of withstanding a 180°F wash temperature, are now available and can be used in cleaning equipment builds. For this study, the authors explored the potential for increasing cleaning process efficiency as a result of an increase in thermal energy due to the use of higher wash temperature. The cleaning equipment selected was an inline cleaner built with high temperature resistant polymer material. For the analysis, standard substrates were used. These were populated with numerous low standoff chip cap components and soldered with both no-clean tin-lead and lead-free solder pastes. Two aqueous based cleaning agents were selected, and multiple wash temperatures and wash exposure times were evaluated. Cleanliness assessments were made through visual analysis of under-component inspection, as well as localized extraction and Ion Chromatography in accordance with current IPC standards.
Technical Library | 2021-01-03 19:24:52.0
Reflow soldering is the primary method for interconnecting surface mount technology (SMT) applications. Successful implementation of this process depends on whether a low defect rate can be achieved. In general, defects often can be attributed to causes rooted in all three aspects, including materials, processes, and designs. Troubleshooting of reflow soldering requires identification and elimination of root causes. Where correcting these causes may be beyond the reach of manufacturers, further optimizing the other relevant factors becomes the next best option in order to minimize the defect rate.
Technical Library | 2020-12-02 20:36:54.0
Industry 4.0 is a topic of much discussion within the electronics manufacturing industry. Manufacturers and vendors are trying to come to terms with what that means. In the most simplistic of terms, Industry 4.0 is a trend toward automation and data exchange within the manufacturing process. This basically requires connectivity and communication from machine to machine within the manufacturing line. The challenge is to collect data from each of the systems within the line and make that data available to the rest of the machines. Without test and inspection, there is no Industry 4.0. The whole purpose of test and inspection is to collect actionable data that may be used to reduce defects and maximize efficiency within the manufacturing line. The goal is to minimize scrap and get a really good handle on those process parameters that need to be put in place to manufacture products the right way the first time. For maximum efficiency, three inspection systems are required within the production line. These are solder paste inspection (SPI) post-solder deposition, automated optical inspection (AOI) post-placement, and AOI post-reflow. This requires a substantial investment; however, the combination of all three inspection machines is really the only true way to provide feedback for each stage of the manufacturing process.
Technical Library | 2019-05-23 10:38:07.0
Solvent and co-solvent cleaning involves the use of engineered solvents in a vapor phase system. The solvents classically used were Class 1 Ozone Depleting Substances, but new types of solvents have been developed that are less environmentally harmful. In some cases, isopropyl alcohol is used with a co-solvent. In these types of cleaning systems, a cloud of boiling vapor solvent is maintained between a boil sump and a cooling coil. When the items to be cleaned are immersed in the vapor cloud, the solvent condenses on the assemblies and acts to dissolve the residues. These processes usually involve a final rinse step outside of the vapor cloud to ensure that all dissolved residues are washed off the assemblies (Figure 1).
Technical Library | 2019-06-05 11:11:06.0
As electronic products increase in functionality and complexity, there is an emphasis on affordability, miniaturization, and energy efficiency. The telecommunications, automotive, and commercial electronic markets are the leading drivers for these trends. These markets see high volume manufacturing with millions of units priced to the fraction of the cent. The choice of the packaging material for the electrical components for these markets can have a substantial effect on the cost of the final product. Therefore plastic encapsulated components are almost universally used in non-military applications over the conventional ceramic or metal electronic packages.
Technical Library | 2020-03-12 14:14:07.0
IPC's APEX EXPO is always exciting & always fun and, most importantly, always beneficial to those who exhibit and attend. From technical conferences to standards committees to new and exciting things on the show floor - APEX 2020 was indeed a success