Technical Library | 2012-05-10 19:48:10.0
First published in the 2012 IPC APEX EXPO technical conference proceedings. Creep corrosion normally happens in the end system, PCB, connectors and components are widely noted due to the exposure of high sulfur environments under elevated humidity. In thi
Technical Library | 2017-05-25 17:07:39.0
Purpose of this research is to identify the factors that directly influence the effectiveness of the fluxing process in selective soldering machines, using the design of experiment methodology with associated factors and levels used in the experiment. Final findings gives directions for set up of the optimal fluxing parameters that will enable appropriate flux appliance and to gain reduction of soldering quality issues which foundations are from this process.
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 | 2018-11-20 21:33:57.0
There are several industry-accepted methods for determining the reliability of flux residues after assembly. The recommended methods of test sample preparation do not always closely mimic the thermal cycle experienced by an assembly. Therefore, extraction from actual assemblies has become a popular method of process control to assess consistency of post-reflow cleanliness. Every method of post-reflow flux residue characterization will depend on the reflow process followed to prepare the coupon.This investigation will focus on the effect of thermal conditions on the remainder of active ingredients in flux residues after assembly with no-clean solder pastes.
Technical Library | 1999-05-07 10:47:00.0
White residue remaining after cleaning circuit board assemblies can be caused by a variety of chemicals and reactions. Rosin and water-soluble fluxes, circuit board resins and epoxies, component materials and other contamination all contribute to this complex chemistry. This paper discusses many of the sources of the residues that seem to be an ever-increasing occurrence.
Technical Library | 2013-04-11 15:43:17.0
With the explosion of growth in handheld electronics devices, manufacturers have been forced to look for ways to reinforce their assemblies against the inevitable bumps and drops that their products experience in the field. One method of reinforcement has been the utilization of underfills to "glue" certain SMDs to the PCB. Bumped SMDs attached to the PCB with a no-clean soldering process offer the unavoidable scenario of the underfill coming in contact with a flux residue. This may or may not create a reliability issue... First published in the 2012 IPC APEX EXPO technical conference proceedings
Technical Library | 2021-10-20 18:21:06.0
The solderability of the SAC305 alloy in contact with printed circuit boards (PCB) having different surface finishes was examined using the wetting balance method. The study was performed at a temperature of 260 _C on three types of PCBs covered with (1) hot air solder leveling (HASL LF), (2) electroless nickel immersion gold (ENIG), and (3) organic surface protectant (OSP), organic finish, all on Cu substrates and two types of fluxes (EF2202 and RF800). The results showed that the PCB substrate surface finish has a strong effect on the value of both the wetting time t0 and the contact angle h. The shortest wetting time was noted for the OSP finish (t0 = 0.6 s with EF2202 flux and t0 = 0.98 s with RF800 flux), while the ENIG finish showed the longest wetting time (t0 = 1.36 s with EF2202 flux and t0 = 1.55 s with RF800 flux). The h values calculated from the wetting balance tests were as follows: the lowest h of 45_ was formed on HASL LF (EF2202 flux), the highest h of 63_ was noted on the OSP finish, while on the ENIG finish, it was 58_ (EF2202 flux). After the solderability tests, the interface characterization of cross-sectional samples was performed by means of scanning electron microscopy coupled with energy dispersive spectroscopy.
Technical Library | 2008-01-24 16:19:43.0
The wave solder process is characterized by a large number of process parameters. To understand them all and their interactions is challenging, particularly when it comes to lead-free soldering. Wave soldering has a number of sub-processes, which include fluxing, preheating, soldering and cooling.
Technical Library | 2013-12-05 17:09:03.0
The functionality of electronic devices continues to increase at an extraordinary rate. Simultaneously consumers are expecting even more and in ever smaller packages. One enabler for shrinking electronics has been the flexible circuit board that allows the circuit board to fit a wide variety of shapes. Flexible printed circuits (FPC) have the capability to be very thin and can have unpackaged components directly attached using surface mount technology (SMT) and flip chip on flex technologies. Bare die can also be thinned and attached very close to the circuit board. However one caveat of high density flexible circuit boards with thin die is that they can be very fragile. The use of back side films and underfill can protect the die making circuits more robust. For underfill to work well it requires good adhesion to the circuit board which can mean that flux residues under the die normally must be removed prior to underfilling.
Technical Library | 2016-11-30 21:30:50.0
Mid-chip solder balling is a defect typically associated with solder paste exhibiting poor hot slump and/or insufficient wetting during the reflow soldering process, resulting in paste flowing under the component or onto the solder resist. Once molten, this solder is compressed and forced to the side of the component, causing mid-chip solder balling.This paper documents the experimental work performed to further understand the impact on mid-chip solder balling from both the manufacturing process and the flux chemistry.
COT specializes in high quality SMT nozzles and consumables for pick and place machines. We provide special engineering design service of custom nozzles for those unique and odd components.
2481 Hilton Drive
Gainesville, GA USA
Phone: (770) 538-0411
.gif)
