Electronics Forum | Thu Jun 25 22:25:24 EDT 2009 | boardhouse
In the life of this product that you have been doing this process, has the material alway's been IT180 material? One problem with Lead free material is that it is more fragile that standard FR4 Epoxy laminate. And is known to have chipping or fractu
Electronics Forum | Wed Jul 01 13:17:39 EDT 2015 | davef
Cheryl Tulkoff and Randy Schueller do a good job summarizing the thinks on pad cratering here: http://www.smta.org/chapters/files/uppermidwest_padcratering.pdf Potential Mitigations to Pad Cratering * Board Redesign * Solder mask defined vs. non-s
Industry News | 2013-10-21 16:05:48.0
IPC – Association Connecting Electronics Industries® presented Committee Leadership, Special Recognition and Distinguished Committee Service Awards at IPC’s Fall Standards Development Committee Meetings last week in Fort Worth, Texas.
Industry News | 2013-07-09 16:18:50.0
Flex Interconnect Technologies (FIT) announces that its CEO Chetan Shah recently held a successful presentation for the Silicon Valley Chapter of the IPC Designer Council.
Technical Library | 2016-10-20 18:13:34.0
Pad cratering failure has emerged due to the transition from traditional SnPb to SnAgCu alloys in soldering of printed circuit assemblies. Pb-free-compatible laminate materials in the printed circuit board tend to fracture under ball grid array pads when subjected to high strain mechanical loads. In this study, two Pb-free-compatible laminates were tested, plus one dicycure non-Pb-free-compatible as control. One set of these samples were as-received and another was subjected to five reflows. It is assumed that mechanical properties of different materials have an influence on the susceptibility of laminates to fracture. However, the pad cratering phenomenon occurs at the layer of resin between the exterior copper and the first glass in the weave. Bulk mechanical properties have not been a good indicator of pad crater susceptibility. In this study, mechanical characterization of hardness and Young’s modulus was carried out in the critical area where pad cratering occurs using nano-indentation at the surface and in a cross-section. The measurements show higher modulus and hardness in the Pb-free compatible laminates than in the dicy-cured laminate. Few changes are seen after reflow – which is known to have an effect -- indicating that these properties do not provide a complete prediction. Measurements of the copper pad showed significant material property changes after reflow.
Technical Library | 2022-01-26 15:26:56.0
In this work an attempt is made to improve the fracture toughness and electrical conductivity of epoxy/glass fiber based laminates by the inclusion of carbon nanotube (CNT) fillers. The fiber orientation of the epoxy/ glass fiber (GF) fabric laminates was optimized based on estimation of mechanical properties. The carboxylic acid functionalized CNTs were incorporated into epoxy matrix by ultra-sonication method. The nano filled epoxy resin was used to prepare laminates with 30/45 GF fabric orientation. The CNT content was varied and its effect on the tensile properties was determined. The fracture toughness of multiphase composites was estimated using single edge notch bend (SENB) test. The presence of CNTs improved the fracture toughness by a crack bridging mechanism. The volume resistivity of multiphase composites was found to be superior to the conventional epoxy/CNT composite. The presence of glass fabric reduces the number of inter-tube contacts contributing to the reduction in volume resistivity.
SMTnet Express, January 27, 2022, Subscribers: 25,985, Companies: 11,506, Users: 27,032 Fracture Toughness Analysis of Epoxy-Recycled Rubber-Based Composite Reinforced with Graphene Nanoplatelets for Structural Applications
SMTnet Express, October 20, 2016, Subscribers: 26,525, Companies: 15,001, Users: 41,289 Analysis of Laminate Material Properties for Correlation to Pad Cratering Carlos Morillo, Yan Ning, Michael H. Azarian, Julie Silk, Michael Pecht.; CALCE Pad
