Technical Library | 2016-12-29 15:37:51.0
The reliabilities of the flux residue of electronic assemblies and semiconductor packages are attracting more and more attention with the adoption of no-clean fluxes by majority of the industry. In recent years, the concern of "partially activated" flux residue and their influence on reliability have been significantly raised due to the miniaturization along with high density design trend, selective soldering process adoption, and the expanded use of pallets in wave soldering process. When flux residue becomes trapped under low stand-off devices, pallets or unsoldered areas (e.g. selective process), it may contain unevaporated solvent, "live" activators and metal complex intermediates with different chemical composition and concentration levels depending on the thermal profiles. These partially-activated residues can directly impact the corrosion, surface insulation and electrochemical migration of the final assembly. In this study, a few application tests were developed internally to understand this issue. Two traditional liquid flux and two newly developed fluxes were selected to build up the basic models. The preliminary results also provide a scientific approach to design highly reliable products with the goal to minimize the reliability risk for the complex PCB designs and assembly processes. This paper was originally published by SMTA in the Proceedings of SMTA International
Technical Library | 2019-09-11 23:33:04.0
There are numerous techniques to singulate printed circuit boards after assembly including break-out, routing, wheel cutting and now laser cutting. Lasers have several desirable advantages such as very narrow kerf widths as well as virtually no dust, no mechanical stress, visual pattern recognition and fast set-up changes. The very narrow kerf width resulting from laser ablation and the very tight tolerance of the cutting path placement allows for more usable space on the panel. However, the energy used in the laser cutting process can also create unwanted products on the cut walls as a result of the direct laser ablation. The question raised often is: What are these products, and how far can the creation of such products be mitigated through variation of the laser cutting process, laser parameters and material handling? This paper discusses the type and quantity of the products found on sidewalls of laser depaneled circuit boards and it quantifies the results through measurements of breakdown voltage, as well as electrical impedance. Further this paper discusses mitigation strategies to prevent or limit the amount of change in surface quality as a result of the laser cutting process. Depending on the final application of the circuit board it may prompt a need for proper specification of the expected results in terms of cut surface quality. This in turn will impact the placement of runs and components during layout. It will assist designers and engineers in defining these parameters sufficiently in order to have a predictable quality of the circuit boards after depaneling.
Technical Library | 2019-09-25 04:36:01.0
What is the main function of hot air dry oven? Drying ovens are devices used to remove moisture and other solvents from the items placed inside them through a forced convection process, collecting it elsewhere so that the object becomes dehydrated. A drying oven causes objects to dry out through evaporation. Drying ovens use convection heating,also called air forced, in which the object is heated through air currents. Water from the object escapes into the air, raising the humidity level and causing the semi-solid membranes inside the oven to absorb the water. The end result is that the oven removes water from the object being dried, leaving it dehydrated. Drying ovens contain a system for forcing convection currents to develop, usually either a fan or turbine, which aids in the heating and drying process by ensuring that the hot air circulates,many ovens are equipped with an adjustable ventilation system that allows the user to ensure that the system has an adequate air supply. For details,pls visit our website: https://climatechambers.com/articles&latestnews/what-is-the-main-function-of-hot-air-dry-oven.html
Technical Library | 2022-10-31 17:25:37.0
Mixed formulation solder alloys refer to specific combinations of Sn-37Pb and SAC305 (96.5Sn–3.0Ag–0.5Cu). They present a solution for the interim period before Pb-free electronic assemblies are universally accepted. In this work, the surfaces of mixed formulation solder alloys have been studied by in situ and real-time Auger electron spectroscopy as a function of temperature as the alloys are raised above the melting point. With increasing temperature, there is a growing fraction of low-level, bulk contaminants that segregate to the alloy surfaces. In particular, the amount of surface C is nearly _50–60 at. % C at the melting point. The segregating impurities inhibit solderability by providing a blocking layer to reaction between the alloy and substrate. A similar phenomenon has been observed over a wide range of (SAC and non-SAC) alloys synthesized by a variety of techniques. That solder alloy surfaces at melting have a radically different composition from the bulk uncovers a key variable that helps to explain the wide variability in contact angles reported in previous studies of wetting and adhesion. VC 2011 American Vacuum Society. [DOI: 10.1116/1.3584821]
Technical Library | 2023-06-12 19:00:21.0
The SMT print process is now very mature and well understood. However as consumers continually push for new electronic products, with increased functionality and smaller form factor, the boundaries of the whole assembly process are continually being challenged. Miniaturisation raises a number of issues for the stencil printing process. How small can we print? What are the tightest pitches? Can we print small deposits next too large for high mix technology assemblies? How closely can we place components for high density products? ...And then on top of this, how can we satisfy some of the cost pressures through the whole supply chain and improve yield in the production process! Today we are operating close to the limits of the stencil printing process. The area ratio rule (the relationship between stencil aperture opening and aperture surface area) fundamentally dictates what can and cannot be achieved in a print process. For next generation components and assembly processes these established rules need to be broken! New stencil printing techniques are becoming available which address some of these challenges. Active squeegees have been shown to push area ratio limits to new boundaries, permitting printing for next generation 0.3CSP technology. Results also indicate there are potential yield benefits for today's leading edge components as well. Stencil coatings are also showing promise. In tests performed to date it is becoming apparent that certain coatings can provide higher yield processing by extending the number of prints that can be performed in-between stencil cleans during a print process. Preliminary test results relating to the stencil coating technology and how they impact miniaturisation and high yield processing will be presented.
New Equipment | Assembly Services
Premium Automatic PCB Support for SMT Processes Ovation’s award-winning Grid-Lok Gold™ automatic substrate support technology provides electronics manufacturers with a robust alternative to costly and often problematic dedicated fixture plates. Set
New Equipment | Board Handling - Conveyors
PROMATION offers two different styles of bare board handling systems. The ESV style bare board loading station holds stacks of PCBs (up to 160 pieces) for line loading. The vacuum head lowers to pick PCBs (from the stack) than raises up and places
New Equipment | Rework & Repair Equipment
Features: 1. 862/872 series uses the newest microcomputer processor PID program control technology, the precise digital show air gun and the iron temperature, the power is change bigger, the elevation of temperature is rapid, it won't influence by t
New Equipment | Test Equipment
Xynetics 1034X Die Prober Test Station with Olympus Microscope head. The eye pieces are Olympus G20x 12.2. We are unable to test this prober. Cables for the controller to connect to the probe station are not available. Contact for freight shipping de
EAO, the Expert for Human Machine Interfaces, is now offering a switch with multicoloured “Halo” illumination for creating highly flexible displays. Designed for use with SMD LEDs, up to 10 different colours can be combined in one switch: eight withi
