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.
Technical Library | 2014-08-14 17:58:41.0
High reliability applications for high performance computing, military, medical and industrial applications are driving electronics packaging advancements toward increased functionality with decreasing degrees of size, weight and power (SWaP) The substrate technology selected for the electronics package is a key enabling technology towards achieving SWaP. Standard printed circuit boards (PWBs) utilize dielectric materials containing glass cloth, which can limit circuit density and performance, as well as inhibit the ability to achieve reliable assemblies with bare semiconductor die components. Ceramic substrates often used in lieu of PWBs for chip packaging have disadvantages of weight, marginal electrical performance and reliability as compared to organic technologies. Alternative materials including thin, particle-containing organic substrates, liquid crystal polymer (LCP) and microflex enable SWaP, while overcoming the limitations of PWBs and ceramic. This paper will discuss the use of these alternative organic substrate materials to achieve extreme electronics miniaturization with outstanding electrical performance and high reliability. The effect of substrate type on chip-package interaction and resulting reliability will be discussed. Microflex assemblies to achieve extreme miniaturization and atypical form factors driven by implantable and in vivo medical applications are also shown.
Technical Library | 2019-05-01 23:18:27.0
Moisture can accelerate various failure mechanisms in printed circuit board assemblies. Moisture can be initially present in the epoxy glass prepreg, absorbed during the wet processes in printed circuit board manufacturing, or diffuse into the printed circuit board during storage. Moisture can reside in the resin, resin/glass interfaces, and micro-cracks or voids due to defects. Higher reflow temperatures associated with lead-free processing increase the vapor pressure, which can lead to higher amounts of moisture uptake compared to eutectic tin-lead reflow processes. In addition to cohesive or adhesive failures within the printed circuit board that lead to cracking and delamination, moisture can also lead to the creation of low impedance paths due to metal migration, interfacial degradation resulting in conductive filament formation, and changes in dimensional stability. Studies have shown that moisture can also reduce the glass-transition temperature and increase the dielectric constant, leading to a reduction in circuit switching speeds and an increase in propagation delay times. This paper provides an overview of printed circuit board fabrication, followed by a brief discussion of moisture diffusion processes, governing models, and dependent variables. We then present guidelines for printed circuit board handling and storage during various stages of production and fabrication so as to mitigate moisture-induced failures.
Technical Library | 2021-03-04 15:22:33.0
Copper clad laminates (CCLs) with low dissipation factor (Df) are urgently needed in the fields of high-frequency communications devices. A novel resin matrix of modified poly (2,6-dimethyl-1,4- phenylene ether) (MPPE) and styrene-ethylene/butylene-styrene (SEBS) was employed in the fabrication of high-frequency copper clad laminates (CCLs). The composites were reinforced by E-glass fabrics, which were modified with phenyltriethoxysilane (PhTES). The composite laminates obtained exhibited impressive dielectric loss of 0.0027 at 10 GHz when the weight ratio of MPPE to SEBS was 5:1.
Technical Library | 2016-09-15 17:10:40.0
This paper describes the purpose, methodology, and results to date of thermal endurance testing performed at the company. The intent of this thermal aging testing is to establish long term reliability data for printed wiring board (PWB) materials for use in applications that require 20+ years (100,000+ hours) of operational life under different thermal conditions. Underwriters Laboratory (UL) testing only addresses unclad laminate (resin and glass) and not a fabricated PWB that undergoes many processing steps, includes copper and plated through holes, and has a complex mechanical structure. UL testing is based on a 5000 hour expected operation life of the electronic product. Therefore, there is a need to determine the dielectric breakdown / degradation of the composite printed circuit board material and mechanical structure over time and temperature for mission critical applications.
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