Technical Library | 1999-05-06 10:36:37.0
Augmented-Fin Air-Cooled Heat Sinks Achieve Higher Performance without Significant Rise in Static Pressure Drop.
Technical Library | 1999-05-06 10:30:06.0
Augmentation of extended surfaces used to dissipate heat increases the overall effectiveness of a heat sink and increases the heat removed per unit volume. This amount of increase depends on the number of augmentations, air flow velocity and ...
Technical Library | 2024-07-24 00:51:44.0
A blade server system (BSS) utilizes voltage regulator modules (VRMs), in the form of quad flat no-lead (QFN) devices, to provide power distribution to various components on the system board. Depending on the power requirements of the circuit, these VRMs can be mounted as single devices or banked together. In addition, the power density of the VRM can be high enough to warrant heat dissipation through the use of a heat sink. Typically, at field conditions (FCs), the BSS are powered on and off up to four times per day, with their ambient temperature cycling between 258C and 808C. This cyclical temperature gradient drives inelastic strain in the solder joints due to the coefficient of thermal expansion (CTE) mismatch between the QFN and the circuit card. In addition, the heat sink, coupled with the QFN and the circuit card, can induce additional inelastic solder joint strain, resulting in early solder joint fatigue failure. To understand the effect of the heat sink mounting, a FEM (finite element model of four QFNs mounted to a BSS circuit card was developed. The model was exercised to calculate the maximum strain energy in a critical joint due to cyclic strain, and the results were compared for a QFN with and without a heat sink. It was determined that the presence of the heat sink did contribute to higher strain energy and therefore could lead to earlier joint failure. Although the presence of the heat sink is required, careful design of the mounting should be employed to provide lateral slip, essentially decoupling the heat sink from the QFN joint strain. Details of the modeling and results, along with DIC (digital image correlation) measurements of heat sink lateral slip, are presented.
Technical Library | 1999-05-06 11:42:16.0
The most reliable and well-designed electronic device can malfunction or fail if it overheats. Considering thermal issues early in the design process results in a thermally conscious system layout and minimizes costs through the use of passive cooling and off-the-shelf components. When thermal issues are left until completion of the design, the only remaining solution may be a costly custom heat sink that requires all the space available. Incorporating a heat sink or a fan into a product after it is fully developed can be expensive, and still may not provide sufficient cooling of the device.
Technical Library | 1999-05-06 11:03:39.0
As microprocessor speeds increase, their power needs rise proportionally. This also puts higher demands on the voltage regulator that feeds the processor chip. In spite of the increased power, the regulator chip tends to remain the same size..
Technical Library | 2014-05-15 14:26:27.0
350mA). Slotted surface showed good performance on both thermal and optical properties of the given 3W green LED.
Technical Library | 1999-05-06 11:18:25.0
The trend toward surface-mount assembly processes is making ball-grid array (BGA) packaging a popular choice for many types of devices, forcing designers to re-examine cooling of these large packages. While devices in BGAs transfer more heat to the board than leaded devices, the style of BGA packages has a large influence on the ability to transfer heat through other pathways, such as a top-mounted heat sink. Physical characteristics of the BGA further constrain the thermal designer. It takes forethought in board design to successfully accommodate devices that require significant heat dissipation. Multiple solutions exist, however, for BGA packages of all types.
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 | 2016-06-23 13:24:56.0
Proper assembly of components is critical in the manufacturing industry as it affects functionality and reliability. In a heat sink assembly, a detailed manual process is often utilized. However, an automated fixture is used whenever applicable.This paper will illustrate the use of strain gauge testing and Finite Element Analysis (FEA) as a simulation tool to evaluate and optimize the heat sink assembly process by manual and automated methods. Several PCBAs in the production line were subjected to the manual and automated assembly process. Strain gauge testing was performed and FEA models were built and run. Results were compared with the goal of improving the FEA model. The updated FEA model will be used in simulating different conditions in assembly. Proposed improvement solutions to some issues can also be verified through FEA.
Technical Library | 2017-11-15 22:49:14.0
While a significant level of voiding can be tolerated in solder joints where electrical conductivity is the main requirement, voiding at any level severely compromises thermal conductivity. For example, in LED lighting modules effective conduction of heat through the 1st level die attach to the substrate and then through the 2nd level attach to the heat sink is critical to performance so that voiding in the solder joints at both levels must be minimized. (...) In this paper, the authors will review the factors that influence the incidence of voids in small and large area solder joints that simulate, respectively, the 1st and 2nd level joints in LED modules and discuss mitigation strategies appropriate to each level. They will also report the results of a study on the effect on the incidence of voids of flux medium formulation and the optimization of the thermal profile to ensure that most of the volatiles are released early in the reflow process.
