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Article
Publication date: 1 February 1987

P. Palanisamy and D.H.R. Sarma

A major drawback of current copper thick‐film technology is the inefficient removal of the organic binder associated with the dielectric material in the low‐oxygen inert gas (N2

Abstract

A major drawback of current copper thick‐film technology is the inefficient removal of the organic binder associated with the dielectric material in the low‐oxygen inert gas (N2) atmosphere of the furnace. In processing large area and/or multilayer substrates, the incomplete binder removal causes deleterious effects which have been well documented. Therefore, it is necessary to remove hydrocarbons and residual carbon from the films in the burn‐out section of the furnace before the films begin developing their characteristic microstructures. However, the atmosphere currently employed is not capable of removing all the carbon and hydrogen in the form of gaseous oxides. In literature, in addition to furnace modifications, several atmosphere modifications and manipulations have been proposed to achieve optimum properties for the fired films. With few exceptions, the scientific basis for such atmosphere modifications and manipulations has been left either unaddressed or obscure. With this background, this paper examines the feasibility of using a reactive gas mixture in the furnace to achieve efficient organic binder removal. Phase stability diagrams are presented to illustrate the stability of (i) carbon, (ii) thick film copper ingredients, (iii) active phases of resistors, and (iv) components of glassy and crystalline phases of dielectrics in selected reactive atmospheres. The stability of certain furnace belt constituents is also addressed. Mass balance calculations are shown to demonstrate the extent of carbon removal and copper oxidation in typical nitrogen atmospheres. Based on the interpretation of thermodynamic data and reaction mechanisms involved, a specific H2‐H2O mixture with nitrogen as the carrier gas is recommended. The approach presented here constitutes a general analytical scheme to understand materials‐atmosphere interactions occurring across a temperature range. Several issues in furnace design are also discussed from the standpoint of gas‐solid reaction kinetics. These deal with the design of gas‐flow systems that facilitate removal of organic binders.

Details

Microelectronics International, vol. 4 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 March 1992

S. Mellul and P. Dupin

A new proprietary nitrogen‐based atmosphere control system (Alix 1) has been developed by L'Air Liquide, allowing control and regulation of the oxygen partial pressure in the…

Abstract

A new proprietary nitrogen‐based atmosphere control system (Alix 1) has been developed by L'Air Liquide, allowing control and regulation of the oxygen partial pressure in the burnout zone of a copper thick‐film firing furnace. The results of a collaboration programme whose objective was to test this system in industrial production conditions at Power Compact are presented. Use of this new system enables improvement of the adhesion results reached by this company in their copper thick‐film hybrid production and ensures a constant level of performance.

Details

Microelectronics International, vol. 9 no. 3
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 January 1990

N. Bandyopadhyay, M. Kirschner and M. Marczi

In the surface mount industry, microelectronic devices are reflow soldered to printed circuit boards with the benefit of mildly activated rosin (RMA) based fluxes. The residues…

Abstract

In the surface mount industry, microelectronic devices are reflow soldered to printed circuit boards with the benefit of mildly activated rosin (RMA) based fluxes. The residues from these fluxes, when not properly cleaned from the component boards, have been cited for decreased circuit life due to corrosion of the solder joints and loss of insulating resistance. Post‐solder cleaning operations with CFC (chlorofluorocarbon) solvents have been deemed environmentally harmful. Hence, there is a great need in the surface mount community for a no‐clean or fluxless solder reflow process. The BOC Group has developed a novel, proprietary process, by which circuit boards and their components are attached with a solder paste under a reactive fluxing atmosphere. The post‐solder residue is non‐corrosive and so minimal that it does not require a post‐solder cleaning operation. The solder joints exhibit good wetting, excellent joint strength and are essentially void‐free. Assembled circuits processed in this way meet all the criteria for ionic cleanliness and surface insulation resistance without post‐solder cleaning.

Details

Soldering & Surface Mount Technology, vol. 2 no. 1
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 22 June 2012

Wei Liu, Yanhong Tian, Lei Yang, Chunqing Wang and Lining Sun

The purpose of this paper is to investigate oxidation and the Au‐Sn reaction of laser reflowed (LR) micro‐solder joints when different protective atmospheres were applied.

Abstract

Purpose

The purpose of this paper is to investigate oxidation and the Au‐Sn reaction of laser reflowed (LR) micro‐solder joints when different protective atmospheres were applied.

Design/methodology/approach

A N2 atmosphere at room temperature, 60°C, 100°C and 130°C, or an air atmosphere at room temperature were utilized in this study. The solder balls were composed of Sn‐2.0Ag‐0.75Cu‐3.0Bi, and 120 μm in diameter. The surface finish of one pad of the joints was 4.0 μm Au/0.1 μm NiFe/0.01 μm Ta, another pad was made of Cu plated with 3.0 μm Au. The laser reflow process time was controlled to within 10 ms. Auger Electron Spectroscopy (AES) was used to identify the oxidation condition of LR solder joints with or without protection from a N2 atmosphere at room temperature. The appearance and cross‐sections of the joints protected by a N2 atmosphere at different temperatures were evaluated using SEM analysis.

Findings

Oxidation of LR solder joints from an air atmosphere was extremely severe, and the surfaces of solder were rough as compared with joints protected by a N2 atmosphere. Au‐rich phases and needle‐like AuSn4 intermetallic compounds (IMCs) formed at the interfaces of the solder and the pads. As the temperature of the N2 atmosphere was increased above 100°C, almost all of the Au‐rich phases disappeared. More needle‐like AuSn4 IMCs formed at the interfaces, as compared with that in joints protected by a N2 atmosphere at room temperature and 60°C. In addition, the orientation of the IMCs had clearly changed.

Originality/value

The results may provide a guide for controlling oxidation and the Au‐Sn reaction of micro‐solder joints during the LR process, and improving the properties of joints between solder and pads with Au surface finishes, by regulating the protective atmosphere.

Details

Soldering & Surface Mount Technology, vol. 24 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 March 1993

R.J. Klein Wassink, M.C. Seegers and M.M.F. Verguld

Several effects of the atmosphere in the soldering oven on both the soldering process itself and the soldering results are discussed. Experiments have been undertaken to compare…

Abstract

Several effects of the atmosphere in the soldering oven on both the soldering process itself and the soldering results are discussed. Experiments have been undertaken to compare the results of soldering in air and in nitrogen containing 10,100 and 1000 ppm oxygen, in which, e.g., discolouration, wettability, solderability after reflow, solder bridging and solder‐ball formation were investigated. Unmounted FR‐4 testboards with both an RMA solder paste of known high quality and a low‐residue paste were used. Mounted test boards were used to analyse the self‐alignment of components and to compare the levels of soldering defects obtained in air and in nitrogen. The test results show that a nitrogen atmosphere containing 1000 ppm of oxygen or less is sufficiently pure to realise improved soldering conditions for most types of components. For the low‐residue paste tested, 1000 ppm is too high, but 100 ppm is sufficiently low. All effects on the soldering process will depend on the amount of oxygen in the gas. To produce an oven atmosphere of nitrogen with a very low amount of O2 (e.g., <100 ppm) is rather expensive, if this oven is to work under production conditions. Will the extra cost of investment and gas consumption be worthwhile in view of a better production yield and higher product quality? The authors explain why they do not believe this to be the case.

Details

Soldering & Surface Mount Technology, vol. 5 no. 3
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 1 January 1987

W. Yext, E.A. Hayduk and C.K. Fisher

Manufacturers of multilayer copper thick‐film circuitry face the challenge of firing parts in an inert nitrogen atmosphere to prevent the copper from oxidising. Nitrogen, while…

Abstract

Manufacturers of multilayer copper thick‐film circuitry face the challenge of firing parts in an inert nitrogen atmosphere to prevent the copper from oxidising. Nitrogen, while protecting the copper from oxidation, offers no efficient mechanism for removing the carbon‐based vehicles used in the copper thick‐film paste. Because of this, carbon residues or soot often deposit on the parts during the firing process. In an attempt to improve the nitrogen furnace atmosphere's ability to remove the vehicles, several gases or gas blends were added to a nitrogen‐based furnace atmosphere. Thick‐film copper conductors and dielectric test pieces were then processed using the various gas blends. The physical properties of adhesion, aged adhesion, solderability, and conductivity of the copper conductor test pieces were studied along with the dielectric properties of dissipation factor, insulation resistance, and dielectric constant. Some of the gases tested included H2, H2O, CO, CO2, and a variety of other gas combinations. Test results demonstrated the atmosphere's ability to effect changes in the physical properties of the parts being processed. A proprietary gas blend was developed which proved effective in removing carbon residues while maintaining the desirable physical properties of the thick films. This work demonstrates the ability of certain gas additives to improve the performance of conventional nitrogen atmospheres when firing copper thick‐film circuitry. With the proper selection of the gas additive, atmosphere flows can be reduced, carbon residues eliminated, and the physical properties of the copper conductors and dielectrics maintained or improved.

Details

Microelectronics International, vol. 4 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 February 1995

M. Warwick, B.S. Chowdhary and N. Stanton

The resin activators' type and quantity in a solder paste have a significant effect on reflow behaviour. These interact with the effects of the oxygen content of the reflow…

Abstract

The resin activators' type and quantity in a solder paste have a significant effect on reflow behaviour. These interact with the effects of the oxygen content of the reflow atmosphere and the condition of the surfaces to be joined. While these parameters might be expected to influence solder paste reflow behaviour, more subtle effects related to the physical characteristics of the resin/solvent solution have also been observed.

Details

Soldering & Surface Mount Technology, vol. 7 no. 2
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 1 January 1992

S. Mellul, D. Navarro and F. Rotman

This paper reports the final results of a development project conducted on nitrogen‐based atmospheres in order to improve the firing of copper thick films. Having shown that…

Abstract

This paper reports the final results of a development project conducted on nitrogen‐based atmospheres in order to improve the firing of copper thick films. Having shown that improvements in copper thick film performance can be obtained under production conditions by the control and regulation of oxygen additions during the first stages of firing, the authors studied the effects on copper thick film systems of other gaseous oxidisers (CO2, N2O, H2O) injected into the nitrogen furnace atmosphere either throughout the entire furnace or into its burnout zone only. SEM examinations of the microstructures of copper films, correlated with properties such as adhesion, solderability and resistivity, allow ideal firing atmosphere conditions for copper thick film manufacturing to be determined: it is necessary to restrict atmosphere doping to the burnout zone; oxygen and water vapour are the most effective gaseous dopants. Some specific equipments have been developed for controlling the injection of these dopants into the furnace atmosphere.

Details

Microelectronics International, vol. 9 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 14 February 2020

Yamid Núñez, Marcio Mafra, Rigoberto E. Morales, Paulo César Borges and Giuseppe Pintaude

This study aims to assess the performance of SAF 2205 duplex stainless steel against pure wear, tribo-corrosion, corrosion and the synergism between wear and corrosion. The effect…

Abstract

Purpose

This study aims to assess the performance of SAF 2205 duplex stainless steel against pure wear, tribo-corrosion, corrosion and the synergism between wear and corrosion. The effect of plasma nitriding conducted at low temperature (380°C) on SAF 2205 steel was analyzed.

Design/methodology/approach

Three systems were used for assessing the synergism between wear and corrosion: tribo-corrosion – wear tests conducted using the micro-scale abrasion test, performed under a slurry of alumina particles containing 3.5% NaCl; pure wear – tests conducted using the previous system but isolated in a glovebox with a 99% N2 atmosphere; and cyclic polarization under 3.5% NaCl solution. A hard nitrided layer of 3 µm thickness was characterized using X-ray diffraction, presenting expanded austenite.

Findings

The wear mode after micro-scale abrasion tests changed in the absence of an oxygen atmosphere. During pure wear, a mixed mode was identified (rolling + grooving), with the grooving mode more intense for the untreated steel. For tribo-corrosion tests, only rolling wear was identified. For all cases, the nitrided samples presented less wear. The corrosion results indicated a higher repassivation potential for the nitrided condition.

Practical implications

The synergism was more positive for the nitrided sample than for the untreated one, which can be considered for surface treatments of duplex stainless steels in practical applications.

Originality/value

A detailed description of wear mechanisms showed a significant change in the presence of oxygen atmosphere, a new approach for isolating pure wear.

Details

Industrial Lubrication and Tribology, vol. 72 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 29 October 2021

Rasiha Nefise Mutlu, Ayşe Nur Acar and Ahmet Murat Gizir

Lightweight, durable and economical materials production has gained considerable importance according to the needs of developing technology. The purpose of this paper is to…

Abstract

Purpose

Lightweight, durable and economical materials production has gained considerable importance according to the needs of developing technology. The purpose of this paper is to develop an new aluminum alloy by powder metalurgy.

Design/methodology/approach

Powder metallurgy, which provides controllably on desired end product, method was applied. Aluminum alloy was created with Al, Zn, Mg, Cu powders and 1.5% Na2[B4O5(OH)4].8H2O added. It was pressed under high pressure and sintered at 600 °C under N2 gas atmosphere. Density, hardness behaviors and thermal properties were determined. Surfaces and crystal structures of samples were characterized.

Findings

The addition of borax made easier grains coming to together, acting as binders and the AlB2 crystal phase was formed. It was also observed that MgZn2, Al2CuMg phases were formed. In this way, the pores between the particles of the material were reduced from 35% to 5% total porosity and the hardness of the material was increased 29 N/mm2 to 45 N/mm2 (Brinell Hardness, HB). The surface properties improved and the hydrophobicity of the surface (from 63° to 102° contact angle with borax) increased. Thus, the heat transfer among atoms get easier and the borax addition decreased specific heat capacity and enthalpy of aluminum–borax samples. This situation was also simulated with the heat transfer module of COMSOL. As result, the energy required reduced. In the other word, sintering process occurred at low temperature and more efficient.

Originality/value

New aluminum alloy has been created from different amounts of Zn, Mg, Cu elemental powders. In addition to literature, relationship of borax and aluminum and other alloying elements on the mechanical, thermophysical and surface properties of new obtained aluminum alloy has been investigated.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

1 – 10 of 245