Mat-Tech Development & Testing

Knowledge Centre

Mat-Tech closely follows international developments in the field of high-tech brazing. Mat-Tech Development & Testing Department has access to new and fundamental research in the field, and is also actively involved in a number of international projects. The knowledge that Mat-Tech acquires is shared with our clients, industry peers and other parties where there is a common ground in high-tech brazing. We are actively sharing our knowledge at fairs, seminars and on this platform as well as other media. Some of the projects Mat-Tech are involved in are as follows:

Residueless Soldering with Bi-In

Soldering of highly stress-sensitive electronic devices (e.g. infrared detectors, photodiodes, Si-based photo multipliers (SiPM), etc.) to printed boards is a delicate issue. Thermo-mechanical stresses built up from cool down after soldering can profoundly affect the overall performance of such devices.
To mitigate this negative effect, soldering temperature has to be kept as low as possible.

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The Young-Laplace Equation

The shape of liquid drop is governed by what is known as the Young-LaPlace equation. It was derived more or less simultaneously by Thomas Young (1804) and Simon Pierre de Laplace (1805).

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Young’s Equation

The concept of surface tension and contact angles as a measure for the wetting capability is ascribed to Thomas Young (1804). This led to what we now know as Young’s law. A short derivation will follow here. Let us consider a small drop in the shape of a spherical cap on a wettable surface.

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Brazing of Aluminium Alloys with Higher Magnesium Content

Successful brazing of any Al alloy requires prior removal of the native surface oxide film, which is usually done by employing a flux. The flux must be capable of displacing the oxide film barrier during brazing and allow the filler metal to flow freely and must prevent the alloy surface from re-oxidizing.

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Diffusion Bonding and Brazing in 3D

Although traditional machining methods of Titanium alloys can generate rather intricate contours and complex shaped parts, fabrication of three-dimensional (3D) components can often be limited and the application of some additive technologies may be required. In the situation when no fusion welding is possible, diffusion bonding and brazing would be precious allies.

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TLPB of Tungsten to Copper-Based Precipitation-Hardened Alloys

Within the International Thermonuclear Experimental Reactor (ITER), one of the most challenging components is the divertor, whose main function is to extract the power from the scrape-off layer of the plasma and to maintain plasma purity.

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The Stiffness of a Vertically Loaded Liquid Bump

In a soldering process the assemblies seeks to minimize the amount of free energy. The weight of the chip compresses the spring formed by the surface of the liquid bump. In order to establish the final height of the assembly one has to find the minimum of the equation.

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Ultimate: Soldering Aluminium at Low Temperature

To design, alloy and process low melting leadfree solder compositions for the purpose of reducing stresses in solder joints to be used in a bio ambient or temperature sensitive environment. In future developments IC technology will be combined with biological objects. For biological components the temperature range for proper functioning is limited.

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SALT I: Soldering Aluminium at Low Temperatureat

Joining of Aluminium and its alloys represents a specific challenge due to the presence of the tenacious oxide film at the metal surface. Successful joining of any Aluminium alloy requires a surface modification action, leading to removal of the native surface oxide film, which can be done through mechanical abrasion or chemical etching or photon absorption.

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SALT II: Soldering Aluminium at Low Temperature

Tracking of assets and personnel, either for security or for efficient managing of resources, is a significant problem in today’s business environment. Theft, losses, misplacement of assets results in billions of dollars worth of increased costs and lost revenues. Companies currently use different technologies to track and locate assets within their work environment, for example the bar code.

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Stress Reduction by Design for Ball Grid Array

BGAs or Ball Grid Arrays are characterized through their large array of solder ball based interconnects at the bottom side of the components. The solder joint serves both as electrical interconnect as well as the mechanical fastener of the component to the board. A simple model of a deflected bump can be made in case one assumes that the bump is built from shearing discs.

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The Molar Specific Heat of Metals

Already in 1819 Pierre Louis Dulong and Alexis Thérèse Petit found that the specific molar heat for metals is nearly a constant. The value turned out to be approximately 25 J/K. This is recognized as 3R, where R is the gas constant. R equals Nk = 8.314 J/K. N is Avogadro’s constant and k is Boltzmann’s constant.

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Joining of High Purity Copper for Compact Linear Collider Structure

The CLIC project designs and builds the next generation particle accelerator. The present material of CLIC accelerating structure disks (cells) is high conductivity Oxygenelectronic(OFE) Cu (fig. 1). Current technology for fabricating the CLIC accelerating structure (disk stack) consists of diffusion bonding the Cu faces of each cell together.

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Solder as Alternative Joining Material for Solar Panel Assembly

In the quest for replacements for the Ag-filled conductive adhesives in the solar panel fabrication, soldering with low-temperature Pb-free alloys is a viable option. Joining of through vias interconnects of Si-based individual cells will be performed via metallization layer made by sintering Ag-based paste containing frit comprising Bi2O3 and other oxides.

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European project CSI: Central Nervous System Imaging

Diseases affecting the brain and the central nervous system (Alzheimer’s, Parkinson’s) are among those with the greatest impact on our society.

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The limitations of Self-Alignment

In a soldering process the assemblies seeks to minimize the amount of free energy. This phenomenon , which takes place when the solder is in the liquid state and can be used to accurately place components is called self-alignment.

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Mat tech

A Non-Linear Spring Model for Solid Material

The properties of a solid material as yield strength, modulus and linear coefficient of thermal expansion CTE can be shown to have an intimate relation. We will assume the material to be characterized well by a non-linear spring.

The Restoring Forces in a Distorted Ball Bump

From the formula it can be seen that that is a coupling between the restoring forces in the vertical and horizontal direction. Compared to the other terms T2,1 is very small.

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