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 | 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 | 2011-10-20 22:03:30.0
Results of FEM modelling of thermal stress analysis in printed circuit boards are given in the article. It is shown that thermal stress alone is not solely caused by differences in coefficients of thermal expansion of individual layers. The emergence of thermal stress is subject to both the layered structure of the wall and given boundary conditions, as well as the existence of a temperature gradient in the direction normal to the surface of the wall. A practical application focuses on the issue of recycling of PCB with the effort to achieve separation of layers due to thermal stress. Role modelling of thermal stress in this area lies in predicting the possibility of separation, depending on the type of thermal stress and material parameters.
Technical Library | 2006-11-01 22:37:23.0
Flip Chip Plastic Ball Grid Array (FCPBGA) modules, when subjected to extreme environmental stress testing, may often reveal mechanical and electrical failure mechanisms which may not project to the field application environment. One such test can be the Deep Thermal Cycle (DTC) environmental stress which cycles from -55°C to 125°C. This “hammer” test provides the customer with a level of security for robustness, but does not typically represent conditions which a module is likely to experience during normal handling and operation.
Technical Library | 2020-02-05 18:20:06.0
Consortium Projects - Thermal Cycling Reliability Consortium projects allow for joint research to investigate the reliability of multiple solder alloys under a variety of environmental stress conditions. Project jointly sponsored by iNEMI and HDP User Group and including CALCE and Universal consortium currently assessing 15 third-generation solder alloys..
Technical Library | 2024-02-05 17:51:01.0
Objective: Drying = reducing the humidity in PCB before soldering Preventing delamination caused by thermal stress after moisture absorption Methods: Drying in convection and/ or vacuum oven Parameters subject to material type, soldering surface, layer count, time to soldering, layout (copper-plated areas)
Technical Library | 2009-11-05 11:17:32.0
Head-in-pillow (HiP), also known as ball-and-socket, is a solder joint defect where the solder paste deposit wets the pad, but does not fully wet the ball. This results in a solder joint with enough of a connection to have electrical integrity, but lacking sufficient mechanical strength. Due to the lack of solder joint strength, these components may fail with very little mechanical or thermal stress. This potentially costly defect is not usually detected in functional testing, and only shows up as a failure in the field after the assembly has been exposed to some physical or thermal stress.
Technical Library | 2020-01-01 17:06:52.0
The majority of electronic failures occur due to thermally induced stresses and strains caused by excessive differences in coefficients of thermal expansion (CTE) across materials.CTE mismatches occur in both 1st and 2nd level interconnects in electronics assemblies. 1st level interconnects connect the die to a substrate. This substrate can be underfilled so there are both global and local CTE mismatches to consider. 2nd level interconnects connect the substrate, or package, to the printed circuit board (PCB). This would be considered a "board level" CTE mismatch. Several stress and strain mitigation techniques exist including the use of conformal coating.
Technical Library | 2008-11-13 00:06:32.0
The electronics industry is facing issues with hot spots, solder joint stresses and Coefficient of Thermal Expansion (CTE) mismatch between PCB and IC substrate. Flip chip type packages for example have very low CTE compared to traditional PCB material. Thus it is necessary to have low CTE printed circuit boards in order to keep solder joint intact with such low CTE packages. There are currently several materials available in the market to address thermal and CTE challenges but each material has its own advantages and limitations...
Technical Library | 2019-03-06 21:26:14.0
Electronic assemblies use a large variety of polymer materials with different mechanical and thermal properties to provide protection in harsh usage environments. However, variability in the mechanical properties such as the coefficient of thermal expansion and elastic modulus effects the material selection process by introducing uncertainty to the long term impacts on the reliability of the electronics. Typically, the main reliability issue is solder joint fatigue which accounts for a large amount of failures in electronic components. Therefore, it is necessary to understand the effect of polymer encapsulations (coatings, pottings and underfills) on the solder joints when predicting reliability.This paper presents the construction and validation of a thermo-mechanical tensile fatigue specimen. The thermal cycling range was matched with potting expansion properties in order to vary the magnitude of tensile stress imposed on solder joints
