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Numerical modelling is used to predict the thermal behaviour of embedded passive components in multi‐layer PCBs. A three‐signal layer PCB, containing embedded resistors of dimensions 0.3 6 0.3mm and thickness 0.1μm, is used to generate thermal design rules that can be applied to a wide range of PCB structures containing embedded passive components. A software package using the design rules can then make fast predictions on the thermal behaviour of heat‐generating components inside such structures.

The purpose of this paper is to discuss laser cutting of FR4, and BT/Epoxy‐based PCB substrates with 355 nm DPSS UV laser.

The effects of various laser conditions such as scanning speed, assisting gas, repetition rate and interval between scans on the heat affected zone (HAZ) and charring are studied. The quality and morphology of laser cut PCB substrates are analyzed with optical microscopy, and scanning electron microscopy (SEM). Also, the laser cut PCB substrates are evaluated by humidity testing and thermal cycle testing.

Multi‐pass cutting at high scanning speed, with O₂ assist gas was found to be able to achieve high quality cutting with little charring. It was also found that a certain time interval between scans and higher repetition rates led to a reduced heat affected zone and less charring.

This paper demonstrates high quality laser cutting of PCB substrates with no delamination, little charring and minimum HAZ. The developed process has important potential applications in the electronics industry.

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.

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.

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.

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.

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.

The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method.

Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced.

The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied.

The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied.

The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

The paper aims to present a modeling method for multi‐layer, multi‐material printed circuit boards (PCBs) in both micro‐structure and board levels.

The method incorporates a multilayer finite element model that is established in two parts: the first part is an elasto‐plastic damaging model, which is presented to model metallic plies in the multi‐layer PCBs, while the second is a bi‐phase model for glass‐fiber/epoxy‐resin composite ply with fiber/matrix structure.

Numerous composite parts and complex material properties of multi‐layer PCBs complicate the reliability of the simulation. Therefore, the board level simulation and the micro‐structure modeling cannot be performed at the same time. A multi‐layer FEM code can solve this problem: with the use of bi‐phase and elasto‐plastic plies in this code, the micro‐structure and board‐level modeling for multi‐layer PCBs can be incorporated.

With the implementation of a virtual boundary method, the current multi‐layer model can be combined with the unit‐cell modeling method to perform detailed analysis at the micro‐structure level.

This paper presents a method for multi‐layer PCB modeling at both the micro‐structure and board levels. It provides a way to individually design the fabric types and the properties of glass fibers, epoxy resin, and copper foil in PCBs, to meet specific reliability requirements. With the proposed modeling, the static and shock responses of optimized PCBs can be analyzed with less computation.

The purpose of this paper is to develop a thermal coupling method of a ball grid array (BGA) assembly during a forced convection reflow soldering process.

The reflow oven was modeled in computational fluid dynamic (CFD) software (FLUENT 6.3.26) while the structural heating BGA package simulation was done using finite element method (FEM) software (ABAQUS 6.9). Both software applications were coupled bi‐directionally using the code coupling software MpCCI.

The convective heat transfer coefficient (h) simulated during the reflow process showed a sufficient view of the changing h in the BGA assembly of each reflow oven. The solder joints were found to experience phase change from solid to liquid during heating and liquid to solid during cooling. These phase changes were present at the melting temperature of the solder joint. The effect of the phase transition point was to cause a large range of temperature difference within the BGA assembly. This situation runs the risk of a skewing defect of components. The simulation results were compared with the experimental results and found to be in good conformity. In addition, the maximum thermal stress from simulation results was trapped in the interfaces between the solder joints and substrate, which tended to form the nucleation of initial crack.

The current study provides a methodology for designing a thermal profile for reflow soldering production.

The findings provide new guidelines for the thermal coupling method. This guideline is very useful for the accurate control of temperature distributions within components and printed circuit boards, which is one of major requirements for achieving high reliability in electronic assemblies.

This paper will focus on the work which was carried out under the Brite‐EuRAM funded project, COMPRISE (BE 96‐3371), the objective of which was to develop new materials and manufacturing processes to embed passive components (resistors, inductors, capacitors) within printed wiring structures fabricated from laminate materials. For the realisation of integrated resistors, a commercially available planar resistor material is incorporated in different test structures. The technology consists of a copper foil of standard thickness on which a resistive layer is deposited by means of electroless plating. For the realisation of capacitors in multi‐layered PCB structures, significant progress was made in the development and fabrication of very thin laminates. Higher dielectric constants of these laminate materials enable the increase of the capacitance per unit area. For inductors, both aircore (no magnetic material) and magnetic core components have been investigated.

The embedding of passive components such as resistors, capacitors and inductors within printed circuit boards (PCBs) is motivated, to a large extent, by the desire for increased miniaturisation of electronic goods. However, resistors and, to a lesser extent, inductors are heat generating devices, and the temperature developed within PCBs as the result of the operation of embedded passives is a significant aspect of the design of a multilayer PCB. Here we investigate, by simulation, temperature fields associated with operation of embedded resistors. It is shown that for board dimensions less than 2cm × 2cm temperatures achieved are higher than those associated with larger boards having identical structures and identical resistor heat generation. Detailed simulations are used to investigate the sensitivity of the temperature rises associated with embedded resistors to copper track coverage and to thermal coupling of the PCB to ambient on its upper and lower surfaces. The implications of these findings are discussed both in the context of the design of real PCBs and in the context of thermal simulation.

As the solution to improve fatigue life and mechanical reliability of packaging structure, the material selection in PCB stack-up and partitioning design on PCB to eliminate the electromagnetic interference by keeping all circuit functions separate are suggested to be optimized from the mechanical stress point of view.

The present paper investigated the effect of RO4350B and RT5880 printed circuit board (PCB) laminates on fatigue life of the QFN (quad flat no-lead) packaging structure for high-frequency applications. During accelerated thermal cycling between −50 °C and 100 °C, the mismatched coefficients of thermal expansion (CTE) between packaging and PCB materials, initial PCB warping deformation and locally concentrated stress states significantly affected the fatigue life of the packaging structure. The intermetallics layer and mechanical strength of solder joints were examined to ensure the satisfactorily soldering quality prior to the thermal cycling process. The failure mechanism was investigated by the metallographic observations using a scanning electron microscope.

Typical fatigue behavior was revealed by grain coarsening due to cyclic stress, while at critical locations of packaging structures, the crack propagations were confirmed to be accompanied with coarsened grains by dye penetration tests. It is confirmed that the cyclic stress induced fatigue deformation is dominant in the deformation history of both PCB laminates. Due to the greater CTE differences in the RT5880 PCB laminate with those of the packaging materials, the thermally induced strains among different layered materials were more mismatched and led to the initiation and propagation of fatigue cracks in solder joints subjected to more severe stress states.

In addition to the electrical insulation and thermal dissipation, electronic packaging structures play a key role in mechanical connections between IC chips and PCB.