Technical Library | 1999-08-27 09:29:49.0
Contract packaging houses have to contend with a large mix of die types and products. Flexibility and quick turnaround of package types is a must in this industry. Traditional methods of die encapsulation, (i.e., use of transfer-molding techniques), are only cost effective when producing a large number of components. Liquid encapsulants now provide similar levels of reliability1, and are cost effective...
Technical Library | 2008-07-10 12:52:18.0
This paper reviews the J-STD-004 and how it is used in flux categorization and selection. It also discusses the major types of flux formulations available, and the design, process and reliability implications of using each type. The purpose of the paper is to help the reader make an informed choice when selecting wave solder fluxes for lead-free processing.
Technical Library | 2017-10-12 15:45:25.0
The risk associated with whisker growth from pure tin solderable terminations is fully mitigated when all of the pure tin is dissolved into tin-lead solder during SMT reflow. In order to take full advantage of this phenomenon, it is necessary to understand the conditions under which such coverage can be assured. A round robin study has been performed by IPC Task group 8-81f, during which identical sets of test vehicles were assembled at multiple locations, in accordance with IPC J-STD-001, Class 3. All of the test vehicles were analyzed to determine the extent of complete tin dissolution on a variety of component types. Results of this study are presented together with relevant conclusions and recommendations to guide high reliability end-users on the applicability and limitations of this mitigation strategy.
Technical Library | 2013-07-11 15:22:40.0
This research paper will focus on the effect of various parameters that are used to reball a BGA and their effect on the overall shear strength. Factors that will be looked at include the type of BGA (SAC305 or 63Sn/37Pb), the alloy used to reball (SAC405 or 63Sn/37Pb), the type of flux used (Water Soluble or No Clean), and the environment in which reballing takes place (Nitrogen or Ambient).
Technical Library | 2023-12-18 21:07:29.0
Selective soldering utilises a nozzle to apply solder to components on the underside of printed circuit boards (PCBs). This nozzle can be moved to either perform dips (depositing solder to a single component) or draws (applying solder to several components in a single movement). The selective soldering methodology thereby allows the process to be tailored to specific joints and allows multiple nozzle types to be used if required on the circuit board. Nozzles can vary by size (internal diameter) and shape (making them suitable for different process types). This is all dictated by board design and process requirements. Selection of the nozzle type is dependent upon the product to be soldered and the desired cycle time. Examples of different nozzle types are shown here. Hand-load selective systems must be programmed with the parameters for multiple solder joints. However, many in-line systems are designed to be modular. This modularity allows for multiple solder stations with different conditions/nozzles to achieve low cycle times. Figure 1 shows the two distinct types of selective soldering systems offered by Pillarhouse International Ltd.
Technical Library | 1999-05-07 10:04:13.0
Powerful desktop multiprocessor systems based on the Intel Architecture (iA) offer a formidable alternative to traditional scientific/engineering workstations for commercial application developers at an attractive costperformance ratio. However, the lack of adequate compiler and runtime library support for multithreading and parallel processing on Windows NT* makes it difficult or impossible to fully exploit the performance advantage of these multiprocessor systems. In this paper we describe the design, development, and initial performance results of the Illinois-Intel Multithreading Library (IML), which aims at providing an efficient and powerful (in terms of types of parallelism it supports) API for multithreaded application developers.
Technical Library | 2012-08-30 21:24:29.0
This paper provides definitions of the different voiding types encountered in Gull Wing solder joint geometries. It further provides corresponding reliability data that support some level of inclusion voiding in these solder joints and identifies the final criteria being applied for certain IBM Server applications. Such acceptance criteria can be applied using various available x-ray inspection techniques on a production or sample basis. The bulk of supporting data to date has been gathered through RoHS server exempt SnPb eutectic soldering operations but it is expected to provide a reasonable baseline for pending Pb-free solder applications.
Technical Library | 2013-09-05 17:44:14.0
Surface plasmon polaritons (SPPs) are localized surface electromagnetic waves that propagate along the interface between a metal and a dielectric. Owing to their inherent subwavelength confinement, SPPs have a strong potential to become building blocks of a type of photonic circuitry built up on 2D metal surfaces; however, SPPs are difficult to control on curved surfaces conformably and flexibly to produce advanced functional devices. Here we propose the concept of conformal surface plasmons (CSPs), surface plasmon waves that can propagate on ultrathin and flexible films to long distances in a wide broadband range from microwave to mid-infrared frequencies.
Technical Library | 2013-08-15 13:12:11.0
An automated visual PCB inspection is an approach used to counter difficulties occurred in human’s manual inspection that can eliminates subjective aspects and then provides fast, quantitative, and dimensional assessments. In this study, referential approach has been implemented on template and defective PCB images to detect numerous defects on bare PCBs before etching process, since etching usually contributes most destructive defects found on PCBs. The PCB inspection system is then improved by incorporating a geometrical image registration, minimum thresholding technique and median filtering in order to solve alignment and uneven illumination problem. Finally, defect classification operation is employed in order to identify the source for six types of defects namely, missing hole, pin hole, underetch, short-circuit, mousebite, and open-circuit.
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.
