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Article
Publication date: 31 July 2007

Winco K.C. Yung and Jijun Zhu

Low temperature co‐fired ceramics (LTCC) material is introduced as an excellent alternative to silicon, glass, or plastic materials for the fabrication of miniaturised analytical…

Abstract

Purpose

Low temperature co‐fired ceramics (LTCC) material is introduced as an excellent alternative to silicon, glass, or plastic materials for the fabrication of miniaturised analytical devices, though it is most widely used in the automotive and microwave industries. The paper aims to study the laser ablation of LTCC material.

Design/methodology/approach

This kind of green tape material is mechanised by excimer laser (KrF, 248 nm) and UV laser (Nd: YAG, 355 nm), and for the first time by infra‐red laser (1,090 nm). The optical photos and the scanning electronic microscope (SEM) photos of the LTCC ablated by different kinds of laser sources are given in this paper.

Findings

When using the UV laser, the tapered structure can be easily seen from the SEM photo. However, a kind of clear and perfect ablation of LTCC can be seen for the first time by the 1,090 nm infra‐red laser ablation.

Originality/value

The laser ablation of LTCC by optical fibre sources is discussed.

Details

Microelectronics International, vol. 24 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 August 1999

M.W. Hendriksen, F.K. Frimpong and N.N. Ekere

CSP (chip scale packaging) and flip chip area array technologies are emerging within the electronics packaging industry to provide solutions capable of fulfilling the…

Abstract

CSP (chip scale packaging) and flip chip area array technologies are emerging within the electronics packaging industry to provide solutions capable of fulfilling the technological demands of computer, telecom and consumer electronic products. However, the full potential of area array attach can only be realised if the next level of interconnect is capable of supporting the fine pitch and high I/O characteristics of emerging CSP and flip chip technology. Celestica has addressed this issue by investigating next generation printed circuit board (PCB) technology, to assess the capability of organic based laminate as a high density interconnect. This paper describes the manufacturing experiments performed to produce a laser microvia interconnect solution. The mechanical performance of the interconnect is also presented to confirm its compatibility with area array assembly.

Details

Microelectronics International, vol. 16 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 June 1999

Franck Rigolet

Conventional processes for cleaning, stripping and surface preparation mainly use solvents or abrasives which can be harmful for the environment, and can also damage the surface…

677

Abstract

Conventional processes for cleaning, stripping and surface preparation mainly use solvents or abrasives which can be harmful for the environment, and can also damage the surface of the material. Moreover, the use of these products generates a large quantity of waste that needs to be reprocessed or discarded. In many cases, laser is the solution to these problems. Its possibilities are still under‐exploited but they are growing with the improvement of the performances of the CO2, YAG and Excimer lasers. This paper describes the laser cleaning process and the benefits which can be obtained.

Details

Assembly Automation, vol. 19 no. 2
Type: Research Article
ISSN: 0144-5154

Keywords

Article
Publication date: 1 June 2000

John H. Lau and Chris Chang

There are many advantages of microvia: it requires a much smaller pad, which saves the board size and weight; with microvia, more chips can be placed in less space or a smaller…

1653

Abstract

There are many advantages of microvia: it requires a much smaller pad, which saves the board size and weight; with microvia, more chips can be placed in less space or a smaller PCB, which results in a low cost; and with microvia, electrical performance improves due to a shorter pathway. Basically, there are five major processes for microvia formation: NC drilling; laser via fabrication including CO2 laser, YAG laser, and excimer; photo‐defined vias, wet or dry; etch via fabrications including chemical (wet) etching and plasma (dry) etching; and conductive ink formed vias, wet or dry. This paper will discuss the materials and processes of these five major microvia formation methods. At the end, eight key manufacturers from Japan will be briefly illustrated for their research status and current capability of producing smallest microvia.

Details

Circuit World, vol. 26 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 March 1994

H.‐J. Krokoszinski and H. Esrom

A novel technology for the interconnection of bare chips in power modules is presented which circumvents the drawbacks of multiple heavy‐wire bonding as well as of reflow…

Abstract

A novel technology for the interconnection of bare chips in power modules is presented which circumvents the drawbacks of multiple heavy‐wire bonding as well as of reflow soldering of many single copper clips inserted into solder preforms. A piece of structured copper‐clad polyimide foil, here called a foil‐clip, is used to provide all required connections, i.e., die‐to‐die and die‐to‐substrate. Hot‐bar soldering or glueing is used for the final joining after adjustment of the foil‐clip to its land areas. Depending on the complexity of the module only a few touch‐downs of the heated tool are required for full assembly. In contrast to the well‐known TAB technique, in foil‐clip technology a copper layer is the top layer (typical thickness: 60 µm). The polyimide (PI) foil (e.g., 25 µm) is used simultaneously as insulation and solder stop layer on the die side. The contact of the photo‐lithographically patterned copper layer with the pads on top of the die and the substrate is achieved by grooving holes into the PI layer which are then filled in a subsequent step with solder or screen‐printed conductive adhesive. Via‐hole formation is achieved by light‐induced ablation. In the first stage of process development a scanning line beam of a pulsed UV excimer laser is moved across the surface of a metal mask containing the pattern to be eroded in the polyimide layer. The present paper describes the optimisation of process parameters in terms of wavelength, pulse rate and fluence variation as well as speed of the substrate displacement during illumination. In future, the use of a novel UV excimer lamp is envisaged which enables large‐area exposure and selective photoetching by using contact metal masks. Furthermore, measurements of the current load capability of the copper interconnects produced by foil‐clips are presented. With an infrared imaging system, the hot‐spot temperature was determined for increasing load current on tracks of different widths and lengths on their way down from high current rectifier diodes to DCB‐module substrates. It is shown that tracks with many squares (N = length/width => ∞) can be loaded with at least I = 22 A. On the other hand, due to cooling through the solder joints, the shortest tracks (N = 1) carry up to 128 A.

Details

Microelectronics International, vol. 11 no. 3
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 December 2002

Klaus Feldmann and Frank Christoph

The production of printed circuit boards (PCB) is facing considerable challenges concerning the demand for higher interconnection density and environmental friendliness. These…

Abstract

The production of printed circuit boards (PCB) is facing considerable challenges concerning the demand for higher interconnection density and environmental friendliness. These demands cannot be satisfied by only optimising the conventional subtractive process chain, but require new production technologies to be developed. The production equipment has to guarantee that the process is carried out in a reliable way and at an acceptable speed. Therefore, the development of new process chains requires a critical review, or even a redesign of suitable manufacturing equipment. The application of simulation tools and “virtual prototyping” can support this process as the technology's impact on the machine design can be evaluated without the need for building costly prototypes. Finally, the costs of the new and current processes can be compared using the simulation results.

Details

Circuit World, vol. 28 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 September 1999

Winco K.C. Yung, J.S. Liu and H.C. Man

Diameter and depth of craters and removing efficiency of the material of RCCR (resin coated copper) used in PCB by a single pulse energy of 355nm YAG laser with a variety of pulse…

Abstract

Diameter and depth of craters and removing efficiency of the material of RCCR (resin coated copper) used in PCB by a single pulse energy of 355nm YAG laser with a variety of pulse energy, pulse width and defocus have been studied in the paper. It is shown that the ablation rates per pulse are much higher when compared with those at 248nm. The crater diameter increases monotonically with the pulse energy. However, when the pulse energy is very high and the power density is higher than 4.0 × 109W/cm2, the crater depth and removing efficiency decrease with the increase of pulse energy. The pulse width has an important influence on the crater diameter and volume when the pulse width changes from 24ns to 38ns, whereas the influence on the crater depth is little. The influences of defocus on ablation results depend on the power density of laser beam. A certain defocus can make both crater diameter and removing efficiency increase for a relatively high power density. Meanwhile, the thermal effect in the process of 355nm laser ablation of RCCR cannot be neglected.

Details

Circuit World, vol. 25 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 January 1998

M. Owen, E. Roelants and J. Van Puymbroeck

In the last two years, laser drilled microvias have become the dominant method for producing blind vias smaller than 150 mm, with over 100 laser drilling machines with a variety…

Abstract

In the last two years, laser drilled microvias have become the dominant method for producing blind vias smaller than 150 mm, with over 100 laser drilling machines with a variety of laser types installed worldwide. Only a few of these systems have been qualified for drilling blind holes in standard glass reinforced FR4. Details a production line at Siemens AUT LP in Karlsruhe, Germany, involving the successful evaluation, introduction, and full production of laser drilling of FR4/glass. An ESI 5100 with Ultraviolet Nd:YAG laser operating at 355nm was chosen for all copper structuring and all microvias less than 150 mm in diameter in thin materials, and a TEA CO2 laser was chosen for thicker constructions, where at least 250 mm holes were required. Production has been running since November 1996. Details the process modifications, design rules, qualified materials, reliability tests, and production experiences.

Details

Circuit World, vol. 24 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 10 June 2014

Linda Ke, Haihong Zhu, Jie Yin and Xinbing Wang

– The purpose of this paper is to report the influence of the peak laser power on laser micro sintering 4-μm nickel powder using Q-switched 1064-nm Nd:YAG laser.

Abstract

Purpose

The purpose of this paper is to report the influence of the peak laser power on laser micro sintering 4-μm nickel powder using Q-switched 1064-nm Nd:YAG laser.

Design/methodology/approach

Experimental study has been performed. Nickel powder with grain size of 4 μm has been utilized. A Q-switching duration of 20-25 μs and rate of 20-40 kHz have been used.

Findings

The peak power intensity is so high that the metal particles and molten pool are blown away, leading to laser micro sintering not being successfully proceeded. The scanning line obtained by continuous-wave (CW) laser looks like a rod owing to balling effect. Using a suitable peak power intensity, a good-shaped sintering line can be obtained because the plasma can protect the molten metal from oxidation, and improve the wettability of the system. In addition, the plasma flattening effect may also contribute to the form of the good-shaped sintering line in pulsed laser sintering regime.

Originality/value

The role of plasma induced by pulsed laser with high peak power intensity has been found during pulsed laser sintering under an ambient environment.

Details

Rapid Prototyping Journal, vol. 20 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 February 1988

A.L. Kenney and J.W. Dally

As microelectronics continue to shrink, it is becoming increasingly difficult and expensive to mechanically drill very small via holes (<0·010 in.). Using lasers and optical…

Abstract

As microelectronics continue to shrink, it is becoming increasingly difficult and expensive to mechanically drill very small via holes (<0·010 in.). Using lasers and optical technology, it is possible to drill any material. Thin circuit board materials of various compositions were investigated as candidates for laser drilling using a 100 watt CO2 laser. Laser variables were pulse frequency, duty cycle, and number of pulses (total energy delivered). Delivered energy seems to be the most critical parameter, and the optimal holes were drilled within a narrow energy band, although there was much data scatter. The best laser drilled holes were of lower quality than that obtainable with mechanical drilling. Photographs of the best holes in all materials are included.

Details

Circuit World, vol. 14 no. 3
Type: Research Article
ISSN: 0305-6120

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