Technical Library | 2009-07-01 09:24:25.0
During the last 5 years, the processes to remove flux residues especially for lead-free and challenging geometries have demonstrated new cleaning obstacles which have to be overcome.i A new methodology has been recently developed to further increase the propensity for successful cleaning.ii At the core of this method is the thermal identification of the residue matrix. Thermal energy changes the physical state, i.e. transitions between liquid, solid and gas phases. By taking advantage of such specific information during phase transitions, the cleaning process can be tailored to such settings, which in turn increases the cleaning success significantly.
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 | 2019-08-14 22:20:55.0
Cleanliness is a product of design, including component density, standoff height and the cleaning equipment’s ability to deliver the cleaning agent to the source of residue. The presence of manufacturing process soil, such as flux residue, incompletely activated flux, incompletely cured solder masks, debris from handling and processing fixtures, and incomplete removal of cleaning fluids can hinder the functional lifetime of the product. Contaminates trapped under a component are more problematic to failure. Advanced test methods are needed to obtain "objective evidence" for removing flux residues under leadless components.Cleaning process performance is a function of cleaning capacity and defined cleanliness. Cleaning performance can be influenced by the PCB design, cleaning material, cleaning machine, reflow conditions and a wide range of process parameters.This research project is designed to study visual flux residues trapped under the bottom termination of leadless components. This paper will research a non-destructive visual method that can be used to study the cleanability of solder pastes, cleaning material effectiveness for the soil, cleaning machine effectiveness and process parameters needed to render a clean part.
Technical Library | 2014-10-16 16:39:12.0
Key points are: *Long-term storage of BGA & QFP products may be required due to: Fab and assembly factory transfers Product obsolescence requiring customers make lifetime/EOL purchases Providing extended service (10+ years) on vehicles Other program needs * Integrity of EOL products in terms of solderability needs to be verified.
Technical Library | 2010-04-15 22:06:32.0
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 | 2016-08-11 15:49:59.0
The challenge for 3D IC assembly is how to manage warpage and thin wafer handling in order to achieve a high assembly yield and to ensure that the final structure can pass the specified reliability requirements. Our test vehicles have micro-bumped die having pitches ranging from 60um down to 30um. The high density of pads and the large die size, make it extremely challenging to ensure that all of the micro-bump interconnects are attached to a thin Si-interposer. In addition, the low standoff between the die and interposer make it difficult to underfill. A likely approach is to first attach the die to the interposer and then the die/interposer sub-assembly to the substrate. In this scenario, the die/interposer sub-assembly is comparable to a monolithic silicon die that can be flip chip attached to the substrate. In this paper, we will discuss various assembly options and the challenges posed by each. In this investigation, we will propose the best method to do 2.5D assembly in an OSAT(Outsourced Assembly and Test) facility.
Technical Library | 2012-01-19 19:14:49.0
The history of multilayered, three-dimensional monolithic microwave integrated circuit (3-D MMIC) technology is described here. Although significant researches were carried out in the second half of 1990’s, still there were many twists and turns before an
Technical Library | 1999-07-20 09:28:38.0
With the increase in heat dissipation from microelectronic devices and the reduction in overall form factors, thermal management bmomes a more and more important element of electronic product design. Both the performance reliability and life expectancy of electronic equipment are inversely related to the component temperature of the equipment...
Technical Library | 2016-05-19 16:03:37.0
As consumers become more reliant on their handheld electronic devices and take them into new environments, devices are increasingly exposed to situations that can cause failure. In response, the electronics industry is making these devices more resistant to environmental exposures. Printed circuit board assemblies, handheld devices and wearables can benefit from a protective conformal coating to minimize device failures by providing a barrier to environmental exposure and contamination. Traditional conformal coatings can be applied very thick and often require thermal or UV curing steps that add extra cost and processing time compared to alternative technologies. These coatings, due to their thickness, commonly require time and effort to mask connectors in order to permit electrical conductivity. Ultra-thin fluorochemical coatings, however, can provide excellent protection, are thin enough to not necessarily require component masking and do not necessarily require curing. In this work, ultra-thin fluoropolymer coatings were tested by internal and industry approved test methods, such as IEC (ingress protection), IPC (conformal coating qualification), and ASTM (flowers-of-sulfur exposure), to determine whether this level of protection and process ease was possible.
Technical Library | 2011-03-03 16:54:47.0
Most of the electronics industry by now knows about tin whiskers. They know whiskers are slim metallic filaments that emanate from the surface of tin platings. They know these filaments are conductive and can cause shorts across adjacent conductors. And they know that these shorts can cause some really bad failures (see nepp.nasa.gov/whisker/ for a list longer than you need). But, with all of this knowledge, the industry is still struggling on how to predict and prevent these "Nefarious Needles of Pain".