Emerald | Circuit World | Table of Contents

Local damage simulations of printed circuit boards based on in-plane cohesive zone parameters

Fri, 10 May 2013 00:00:00 +0100

Abstract

Purpose – The purpose of this paper is to analyse, in a finite element simulation, the failure of a multilayer printed circuit board (PCB), exposed to an impact load, to better evaluate the reliability and lifetime. Thereby the focus was set on failures in the outermost epoxy layer. Design/methodology/approach – The fracture behaviour of the affected material was characterized. The parameters of a cohesive zone law were determined by performing a double cantilever beam test and a corresponding simulation. The cohesive zone law was used in an enriched finite element local simulation model to predict the crack initiation and crack propagation. Using the determined location of the initial crack, the energy release rate at the crack tip was calculated, allowing an evaluation of the local loading situation. Findings – A good concurrence between the simulated and the experimentally observed failure pattern was observed. Calculating the energy release rate of two example PCBs, the significant influence of the chosen type on the local failure behaviour was proven. Originality/value – The work presented in this paper allows for the simulation and evaluation of failure in the outermost epoxy layers of printed circuit boards due to impact loads.

PCB base material qualifications: discrepancies between supplier recommendations, customer expectations and reality

literatinetwork@emeraldinsight.com (Sylvia Ehrler) — Fri, 10 May 2013 00:00:00 +0100

Abstract

Purpose – Today a large variety of printed circuit board (PCB) base materials exists on the market and new ones are added frequently. The base material suppliers, having good original equipment manufacturer (OEM) marketing, usually present the materials in an early development stage to the end customers. The customers, on the other hand, expect from their PCB suppliers that the materials are fully characterized and that qualification samples are available immediately. In many cases, the process recommendations given to the PCB manufacturers are very generic (“like FR4”), insufficient, or not practicable (“8?hours baking time”). However, optimized processing ensures the reliability of the finished PCBs, starting from general leadfree compatibility to CAF testing. This demonstrates the importance of thoroughly verified process parameters and of very specific process recommendations to minimize the number of costly and time-consuming iterations, and to be able to meet the goal of submitting qualification samples and functional PCBs in minimum time. The purpose of this paper is to show the minimum required PCB processing recommendations, and why these have to be fixed by the material supplier before commercialization of a new base material. Design/methodology/approach – The paper examines the base material suppliers' situation, customer expectations and reality and the PCB manufacturers' expectations. Findings – The paper gives the reasons and consequences of early base material marketing. Originality/value – The paper analyses today's PCB base materials market and shows the reasons and consequences of early base material marketing. Also, the minimum requirements by PCB fabricators concerning processing recommendations are given.

Challenges and developments of micro drill bit for printed circuit board: a review

literatinetwork@emeraldinsight.com (Hongyan Shi, Hui Li) — Fri, 10 May 2013 00:00:00 +0100

Abstract

Purpose – The purpose of this paper is to present a clear picture of the challenges of micro drill bit and the developments of novel micro-drill bits for flexible circuit boards, environmental-friendly printed circuit boards (PCBs), high aspect ratio drill bit and ultra-small micro drill bit, as well as the developments of geometry design of micro drill bit. Design/methodology/approach – The paper details the developments trend and challenges of micro drill and PCBs first. Then the current research status of novel micro drill bits for flexible circuit boards, environmental-friendly PCBs, high aspect ratio drill bit, ultra-small micro drill bit are described. Finally, the developments of geometry design and drilling process are reviewed. Findings – To achieve excellent performance for drilling flexible PCB, a large helical angle, large flute/land ratio and small web thickness that guarantee the sharp evacuation capability, are adopted in drill bit design. A small helix angle and an appropriate primary face angle are employed for drill bit to process environmental-friendly printed circuit boards. It is beneficial to implement big helix angle, small primary face angles and small point angles in the design of ultra-small micro drill bit. An optimum web thickness and step feed should be taken into consideration in high aspect ratio drill bits design. Originality/value – The paper reviews different solutions of micro drill bits for the state-of-the-art PCB and the developments of geometry design of drill bit for printed circuit boards.

Experimental investigation of microdrilling of printed circuit board

Fri, 10 May 2013 00:00:00 +0100

Abstract

Purpose – The purpose of this paper is to investigate the cutting mechanism of drilling printed circuit board (PCB) and to optimize the drilling parameters for decreasing burr size and thrust force. Design/methodology/approach – An experimental study was carried out to investigate the effect of drilling parameters on thrust force and burr formation. The drilling process of PCB was divided by the variation of drilling force signals. Analysis of variance (ANVONA) was carried out for burr size and thrust force. Desirability function method was used in multiple response optimization, to find the best drilling parameters. Findings – Enter burr and exit burr have different morphologies and types. The generation of enter burr is mainly caused by burr bending which can be observed in micrographs, whereas the generation of exit burr is more complicated than enter burr; both burr breakup and burr bending are observed in exit burrs. In the selected area, the optimized spindle speed and feed rate for drilling PCB is 12?krev/min and 6?mm/s, respectively. Research limitations/implications – In this paper, hole wall roughness and tool wear were not considered in the optimization of drilling parameters. The future research work should consider them. Originality/value – This paper investigates the mechanism of burr formation and thrust force in drilling PCB and then optimizes the drilling parameters to decrease the burr formation and thrust force.

Micro UHMW-PE column array molded by the utilization of PCB as mold insert

Fri, 10 May 2013 00:00:00 +0100

Abstract

Purpose – The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro-hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded. Design/methodology/approach – Micro carbide drill bits of which the diameters are 100.0?µm, 150.0?µm and 200.0?µm, respectively, are used for drilling the PCB to form a micro-hole array insert. Next, two kinds of various ultra-high molecule weight polyethylene (UHMW-PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro-hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW-PE can be rapidly filled into the cavity. Finally, micro-column array plastic parts are successfully prepared. Findings – The micro-hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW-PE powder with the grain diameter of about 350?µm, the diameter replication rates of the micro-column array plastic parts become good in order with the increased micro-hole diameter of the PCB. When the fine UHMW-PE powder with the grain diameter of about 80?µm is adopted, the diameter replication rates of the micro-column array plastic parts become good in order with the decreased micro-hole diameter of the PCB. Originality/value – In this paper, the micro-column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.

Mesmoproc – implementation of a maskless electrochemical surface modification process

literatinetwork@emeraldinsight.com (Martin Goosey, Sudipta Roy) — Fri, 10 May 2013 00:00:00 +0100

The Rainbow process: I have seen it! It works!

literatinetwork@emeraldinsight.com (Pete Starkey) — Fri, 10 May 2013 00:00:00 +0100

Polar Instruments’ Speedstack Materials Library extended to include new PCB materials from Ventec Europe

Fri, 10 May 2013 00:00:00 +0100

New JTAG support option adds boundary-scan capability to 6TL functional testers

Fri, 10 May 2013 00:00:00 +0100

International diary

Fri, 10 May 2013 00:00:00 +0100

Schweizer AG announce trading figures for 2012

Fri, 10 May 2013 00:00:00 +0100

Orbotech opens new facility in Jena, Germany

Fri, 10 May 2013 00:00:00 +0100

Ventec AS9100C approval fully certificated

Fri, 10 May 2013 00:00:00 +0100

20 percent growth in 2012 for PCB manufacturer

Fri, 10 May 2013 00:00:00 +0100

HDP User Group announces new member company

Fri, 10 May 2013 00:00:00 +0100

ERE continues advancement in imaging technology with Orbotech LDI

Fri, 10 May 2013 00:00:00 +0100

Editorial

literatinetwork@emeraldinsight.com (Martin Goosey) — Fri, 10 May 2013 00:00:00 +0100

Institute of Circuit Technology Northern Seminar, Hartlepool, 6 November 2012

literatinetwork@emeraldinsight.com (Pete Starkey) — Fri, 10 May 2013 00:00:00 +0100

6th International Symposium on Tin Whiskers

literatinetwork@emeraldinsight.com (Martin Goosey) — Fri, 10 May 2013 00:00:00 +0100

Large area electronics: addressing the applications challenge

literatinetwork@emeraldinsight.com (Martin Goosey) — Fri, 10 May 2013 00:00:00 +0100

EIPC Winter Conference

literatinetwork@emeraldinsight.com (John Ling) — Fri, 10 May 2013 00:00:00 +0100

Invotec Group Ltd appoints new sales account manager for south and south west

Fri, 10 May 2013 00:00:00 +0100

Jason Maupin promoted to Vice President, Enthone Americas

Fri, 10 May 2013 00:00:00 +0100