Technical Library | 2007-09-13 16:58:52.0
With the use of laser light for reflow having been established, all that remains is to apply it to best effect. Each time a laser is fired, it pumps a specific amount of energy at a particular wavelength to a particular point in space. Where technique comes in is choosing where and for how long to apply that light along with the application of accessory equipment to optimize solder paste reflow. This presentation covers the specifics of how to determine which process choices are the right process choices based on the needs of your product to maximize yield and throughput.
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".
Technical Library | 2011-05-05 16:17:34.0
Passives account for a very large part of today’s electronic assemblies. This is particularly true for digital products such as cellular phones, camcorders, and computers. Market pressures for new products with more features, smaller size and lower cost v
Technical Library | 2011-06-09 20:28:30.0
QFN Description: A QFN package is a QUAD-FLAT-NO LEAD device. This package is small and lightweight and has no leads (unlike a gull wing or J-leaded device). QFN’s have a thermal pad (paddle) on the bottom side of the part that offers heat dissipation and
Technical Library | 2007-03-13 14:31:11.0
Do you have an idea for an electronic product, the next must-have gadget, music or video system, time saver, or the greatest problem-solving device that was ever invented? Before you begin designing the product, there are a number of tasks that you must complete and issues that you must resolve before you have an actual product design that can be produced, marketed, and sold. This article will provide you with some guidelines to assist you in getting your idea turned into a successful design. Other issues, such as whether or not to apply for a patent for your product idea and in detail how a particular product should be advertised or marketed will not be addressed in this article.
Technical Library | 2013-06-20 14:33:12.0
With today's consumer technologies driving the need for denser and more compact devices, the assembly process for surface mounted devices has becoming increasingly more difficult. With the mixture of components requiring a broader range of print deposition volume, various techniques are in use in an attempt to ensure consistent and appropriate paste volume is achieved. Some of these techniques include step etching a stencil locally on a targeted device, promoting electroformed smooth wall nickel stencils, through to laser cutting newer grade stencil materials. This paper focuses on the relevant attributes that affect the properties of solder paste release and introduces the effects of surface free energy with respect to key elements that make up the stencil printing process.
Technical Library | 2014-06-12 16:40:19.0
Occurrence of popcorn in IC packages while assembling them onto the PCB is a well known moisture sensitive reliability issues, especially for surface mount packages. Commonly reflow soldering simulation process is conducted to assess the impact of assembling IC package onto PCB. A strain gauge-based instrumentation is developed to investigate the popcorn effect in surface mount packages during reflow soldering process. The instrument is capable of providing real-time quantitative information of the occurrence popcorn phenomenon in IC packages. It is found that the popcorn occur temperatures between 218 to 241°C depending on moisture soak condition, but not at the peak temperature of the reflow process. The presence of popcorn and delamination are further confirmed by scanning acoustic tomography as a failure analysis.
Technical Library | 2018-12-12 22:20:22.0
Numerous 3D stack packaging technologies have been implemented by industry for use in microelectronics memory applications. This paper presents a reliability evaluation of a particular package-on-package (PoP) that offers a reduction in overall PCB board area requirements while allowing for increases in functionality. It utilizes standard, readily available device packaging methods in which high-density packaging is achieved by: (1) using standard "packaged" memory devices, (2) using standard 3-dimensional (3-D) interconnect assembly. The stacking approach provides a high level of functional integration in well-established and already functionally tested packages. The stack packages are built from TSOP packages with 48 leads, stacked either 2-high or 4-high, and integrated into a single dual-flat-no-lead (DFN) package.
Technical Library | 2019-09-24 15:41:53.0
This paper focuses on three different coating material groups which were formulated to operate under high thermal stress and are applied at printed circuit board manufacturing level. While used for principally different applications, these coatings have in common that they can be key to a successful thermal management concept especially in e-mobility and lighting applications. The coatings consist of: Specialty (green transparent) liquid photoimageable solder masks (LPiSM) compatible with long-term thermal storage/stress in excess of 150°C. Combined with the appropriate high-temperature base material, and along with a suitable copper pre-treatment, these solder resists are capable of fulfilling higher thermal demands. In this context, long-term storage tests as well as temperature cycling tests were conducted. Moreover, the effect of various Cu pre-treatment methods on the adhesion of the solder masks was examined following 150, 175 and 200°C ageing processes. For this purpose, test panels were conditioned for 2000 hours at the respective temperatures and were submitted to a cross-cut test every 500 h. Within this test set-up, it was found that a multi-level chemical pre-treatment gives significantly better adhesion results, in particular at 175°C and 200°C, compared with a pre-treatment by brush or pumice brush. Also, breakdown voltage as well as tracking resistance were investigated. For an application in LED technology, the light reflectivity and white colour stability of the printed circuit board are of major importance, especially when high-power LEDs are used which can generate larger amounts of heat. For this reason, a very high coverage power and an intense white colour with high reflectivity values are essential for white solder masks. These "ultra-white" and largely non-yellowing LPiSM need to be able to withstand specific thermal loads, especially in combination with high-power LED lighting applications. The topic of thermal performance of coatings for electronics will also be discussed in view of printed heatsink paste (HSP) and thermal interface paste (TIP) coatings which are used for a growing number of applications. They are processed at the printed circuit board manufacturing level for thermal-coupling and heat-spreading purposes in various thermal management-sensitive fields, especially in the automotive and LED lighting industries. Besides giving an overview of the principle functionality, it will be discussed what makes these ceramic-filled epoxy- or silicone-based materials special compared to using "thermal greases" and "thermal pads" for heat dissipation purposes.
Technical Library | 2014-05-29 13:48:14.0
Electronics packaging based on stress-engineered spring interconnects has the potential to enable integrated IC testing, fine pitch, and compliance not readily available with other technologies. We describe new spring contacts which simultaneously achieve low resistance ( 30 μm) in dense 2-D arrays (180 ~ 180-µm pitch). Mechanical characterization shows that individual springs operate at approximately 150-µN force. Electrical measurements and simulations imply that the interface contact resistance contribution to a single contact resistance is This paper suggests that integrated testing and packaging can be performed with the springs, enabling new capabilities for markets such as multichip modules.