Technical Library | 2019-07-10 23:36:14.0
Pockets of gas, or voids, trapped in the solder interface between discrete power management devices and circuit assemblies are, unfortunately, excellent insulators, or barriers to thermal conductivity. This resistance to heat flow reduces the electrical efficiency of these devices, reducing battery life and expected functional life time of electronic assemblies. There is also a corresponding increase in current density (as the area for current conduction is reduced) that generates additional heat, further leading to performance degradation.
Technical Library | 2023-01-17 17:12:33.0
Reflowed indium metal has for decades been the standard for solder thermal interface materials (solder TIMs or sTIMs) in most high-performance computing (HPC) TIM1 applications. The IEEE Heterogeneous Integration Thermal roadmap states that new thermal interface materials solutions must provide a path to the successful application of increased total-package die areas up to 100cm2. While GPU architectures are relatively isothermal during usage, CPU hotspots in complex heterogeneously-integrated modules will need to be able to handle heat flux hotspots up to 1000W/cm2 within the next two years. Indium and its alloys are used as reflowed solder thermal interface materials in both CPU and GPU "die to lid/heat spreader" (TIM1) applications. Their high bulk thermal conductivity and proven long-term reliability suit them well for extreme thermomechanical stresses. Voiding is the most important failure mode and has been studied by x-ray. The effects of surface pretreatment, pressure during reflow, solder flux type/fluxless processing, and preform design parameters, such as alloy type, are also examined. The paper includes data on both vacuum and pressure (autoclave) reflow of sTIMs, which is becoming necessary to meet upcoming requirements for ultralow voiding in some instances.
Technical Library | 2019-06-12 10:33:58.0
The success of ball grid array (BGA) placement on electronic assemblies is as much a matter of proper preparation and planning, as it is technique. In some designs, it is more appropriate to apply BGAs using a rework station that isolates the placement of the device, without subjecting the entire assembly to thermal reflow. This is especially beneficial in board constructions where the number of BGAs is limited, and the application of the solder paste is difficult, due to small pitch features that stretch the limitation of the stencil construction. Another application for rework stations, involves very large and thermally conductive BGAs, which will not uniformly reflow with other components on the assembly, and may require special process parameters for their proper placement. The most common use of BGA rework stations are for assemblies requiring BGA removal and replacements due to failures in the initial assembly stage.
Technical Library | 2021-09-02 08:17:07.0
We are a professional manufacturer of PCB depaneling machines, which is workable for all boards, including flex and regid boards, v-scored boards and routed boards. Laser pcb depaneling is non-contact way without mechanical stress,this solution is good for modern precision PCB depaneling. It has below advantages: 1. No dust The production environment of the circuit board industry is carried out in the dust-free workshop. The traditional pcb depaneling equipment, such as blade moving type machine, will inevitably produce residues and micro powder, which will pollute the 10000 and 1000 class dust-free workshops and affect the conductivity of products. The UV laser PCB cutting machine is a vaporization processing process, which will not produce dust and is conducive to the conductivity of the product. 2. High cutting precision The processing gap of high-precision traditional processing equipment can not reach the gap width of less than 100 microns, which will cause certain damage to the lines on the edge or PCBA circuit board containing components. The focus spot of the laser cutting machine is small, and the ultraviolet cold processing mode has little thermal impact on the edge of the circuit board. The cutting position accuracy is less than 50 microns, and the cutting size accuracy is less than 30 microns, which will not affect the edge of the circuit board, and the precision is high. 3. No stress Traditional processing methods generally have V-grooves, which will cause certain damage to the board in the manufacturing process. The UV laser PCB cutting machine can directly cut the bare board without making V-grooves. In addition, the traditional processing methods directly use tools to act on the circuit board, especially the stamping method has a great impact on the circuit board, which is easy to cause board deformation. The laser cutting machine is a non-contact processing mode, which acts on the surface of the material through the high-energy beam, which will not cause the influence of stress and the deformation and damage of the circuit board. 4. For special-shaped cutting, it is easy to automate The UV laser PCB cutting machine can cut for any shape without replacing any props and fixtures, and without steel mesh. The same equipment can meet special-shaped and straight-line cutting, which is easy to realize assembly line automatic production and high flexibility. It is easy to improve production efficiency and save production process and production cycle. In particular, it can quickly and efficiently meet the needs of rapid proofing, directly import the drawing, and then locate the cutting. 5. High compatibility The UV laser PCB cutting machine can process the materials around the circuit board, such as PCB, FPC, covering film, pet, reinforcing board, IC, ultra-thin metal cutting, etc. it has strong practicability, is compatible with the processing of a variety of materials, is easy to operate, can be imported into the drawing, does not need to adjust any mechanical parts, and is easy to operate and maintain. 6. Good cutting edge effect The cutting edge is smooth and neat without burr. It can be processed and formed directly according to the size of the drawing, which is conducive to improving the yield of the product. It can be directly installed into the subsequent process without further processing. For more details about UV laser depaneling, please feel free to contact us. www.pcbdepanelingrouter.com
Technical Library | 2017-05-04 17:35:01.0
Most of today's printed circuit board base materials are anisotropic and it is not possible to use a simple method to measure thermal conductivity along the different axis, especially when a good accuracy is expected. Few base material suppliers' datasheet show X, Y and Z thermal conductivities. In most cases, a single value is given, moreover determined with a generic methodology, and not necessarily adapted to the reality of glass-reinforced composites with a strong anisotropy.After reminding of the fundamentals in thermal science, this paper gives an overview of the state-of the art in terms of thermal conductivity measurement on PCB base materials, and some typical values. It finally proposes an innovative method called transient fin method, and associated test sample, to perform reliable and consistent in plane thermal conductivity measurement on anisotropic PCB base materials.
Technical Library | 2014-02-27 15:30:20.0
Silicon dioxide is normally used as filler in underfill. The thermal conductivity of underfill is less than 1 w/mk, which is not able to meet the current flip chip application requirements such as 3D stacked multi-chips packaging. No matter which direction the heat will be dissipated through PCB or chip, the heat has to pass through the underfill in 3D stacked chips. Therefore the increase of thermal conductivity of underfill can significantly enhance the reliability of electronic devices, particularly in 3D package devices
Technical Library | 2020-10-14 14:18:13.0
Thermally conductive adhesives provide many advantages over traditional mechanical fastening techniques. Specifically, they use less material and space and are more amenable to automation than existing solutions. The thermal and mechanical properties of these materials are well understood but little work has been done to characterize and understand their toughness and fracture behavior. This paper presents the effects of filler loading as well as matrix composition on the fracture toughness of thermally conductive silicone adhesives. It was observed that the fracture toughness of these materials increased significantly with initial filler loading, and that the mechanical properties and fracture toughness depended on the molecular architecture of the matrix used.
Technical Library | 2017-11-08 23:22:04.0
Due to the ongoing trend towards miniaturization of power components, the need for increased thermal conductivity of solder joints in SMT processes gains more and more importance. Therefore, the role of void free solder joints in power electronics becomes more central. Voids developed during soldering reduce the actual thermal transfer and can cause thermal damage of the power components up to their failure. For this reason, the company has developed a new technique to minimize the formation of these voids during the soldering process.
Technical Library | 2020-10-14 14:33:36.0
Epoxy based adhesives are prevalent interface materials for all levels of electronic packaging. One reason for their widespread success is their ability to accept fillers. Fillers allow the adhesive formulator to tailor the electrical and thermal properties of a given epoxy. Silver flake allow the adhesive to be both electrically conductive and thermally conductive. For potting applications, heat sinking, and general encapsulation where high electrical isolation is required, aluminum oxide has been the filler of choice. Today, advanced Boron Nitride filled epoxies challenge alternative thermal interface materials like silicones, greases, tapes, or pads. The paper discusses key attributes for designing and formulating advanced thermally conductive epoxies. Comparisons to other common fillers used in packaging are made. The filler size, shape and distribution, as well as concentration in the resin, will determine the adhesive viscosity and rheology. Correlation's between Thermal Resistance calculations and adhesive viscosity are made. Examples are shown that determination of thermal conductivity values in "bulk" form, do not translate into actual package thermal resistance. Four commercially available thermally conductive adhesives were obtained for the study. Adhesives were screened by shear strength measurements, Thermal Cycling ( -55 °C to 125 °C ) Resistance, and damp heat ( 85 °C / 85 %RH ) resistance. The results indicate that low modulus Boron Nitride filled epoxies are superior in formulation and design. Careful selection of stress relief agents, filler morphology, and concentration levels are critical choices the skilled formulator must make. The advantages and limitations of each are discussed and demonstrated.
Technical Library | 2018-11-07 20:48:01.0
Glass offers a number of advantages as a dielectric material, such as a low coefficient of thermal expansion (CTE), high dimensional stability, high thermal conductivity and suitable dielectric constant. These properties make glass an ideal candidate for, among other things, package substrate and high-frequency PCB applications. We report here a novel process for the production of printed circuit boards and integrated circuit packaging using glass as both a dielectric medium and a platform for wiring simultaneously.
