Martin Hirman

Influence of reflow soldering profiles on creation of IMC at the interface of SnBi/Cu

The paper describes the effect of the solder profile on the formation of an intermetallic layer in the solder composition of 57.6% Bi-42% Sn-0.4% Ag. Soldered joints were made by soldering of chip resistors of 1206 size with different soldering reflow profiles. Solder pads on the PCB are made of copper therefore they mainly make Cu6Sn5 IMC. This layer has an effect on the mechanical strength of the soldered joint. Samples are measured by using the shear strength test. The thickness of the IMC layer is measured by Confocal Laser Scanning Microscope. IMC layer thickness grows with greater delivered energy into the joint during soldering.

Optimization of solder paste quantity considering the properties of solder joints

Purpose The purpose of this paper is to find an optimum between the quantity of solder paste and the desired properties of the soldered joint. A reduction of solder paste quantity is recognized as an opportunity to save money. On the other hand, the quantity of solder paste significantly influences the final properties of the soldered joint. The purpose is also to design recommendations for manufacturers of electronic assemblies. Design/methodology/approach The processing of the paper was initiated by a literature review. The expert analysis was the next step. The result of analysis was a fishbone diagram. Subsequently, the experiment was designed. Seven types and three volume of solder pastes and two aperture shapes of the stencil were used. The measured parameters were mechanical strength, electrical resistance, voids area and intermetallic compound (IMC) thicknesses. The results of the experiment were evaluated and recommendations for practice were defined. Findings The carried out research has confirmed the influence of solder paste quantity on the shear strength, electrical resistance, voids area and IMC thickness of solder joint. The article presents the results achieved for solders Sn42Bi58, Sn42Bi57.6Ag0.4, SnAg3.0Cu0.5, SnCu0.7Ag1.0NiGe, SnAg3.5Bi0.5In8.0 and Sn62.5Pb36.5Ag1.0. Reduction of solder paste quantity down to 74 per cent (i.e. one quarter of quantity) decreases mechanical shear strength less than 10 per cent. Recommendations relating to the optimal reduction of solder paste quantity have been designed for each solder paste. Originality/value Contribution of the paper is impact assessment of solder paste quantity on the properties of the soldered joint. It was carried out a large number of experiments and measurements which verify this effect. Such a comprehensive overview of the results is not yet available in the literature. Recommendations for manufacturers of electronic assemblies are also the benefit of article.

A comparison of the shear strength of conductive adhesives and soldering alloys

This paper describes the influence of the cure schedule on the shear strength of the joint glued by EPO-TEK® H20S and 8331S. This work also describes the influence of solder alloy types on the shear strength of the solder joint. Joints were made by soldering and gluing of chip resistors 1206, 0805 and 0603 with different temperature profiles on rigid and flexible substrates. For soldering profiles were calculated heating factors. These profiles have an effect on the mechanical strength of the joint. Samples are measured after curing/soldering process by using shear strength test.

Adhesion improvement of Thick Printed Copper film on alumina substrates by controlling of oxygen level in furnace

This paper deals with an adhesion measuring of samples prepared by prospective TPC (Thick Printed Copper) technology. The TPC technology is used for power electronic substrate manufacturing. Copper film is screen printed on alumina substrate and fired in nitrogen atmosphere. Oxygen level dependence on adhesion of copper film to alumina base and copper film solderability was observed in this paper.

Influence of flexible substrate roughness with aerosol jet printed pads on the mechanical shear strength of glued joints

This paper presents a research focused on Aerosol Jet printed pads adhesion improvement for electrically conductive adhesives (ECA) testing. The Aerosol Jet technology is able to use nanoparticle inks for deposition process. The adhesion of the ink to the substrate is crucial especially when you realize printing on flexible substrates. The paper will show a new method of adhesion improvement by plasma treatment and fine sandpaper grinding. The adhesion testing was realized by shear strength test of glued joints. Ten SMD chip resistors 1206 were mounted to the electrically conductive adhesive on aerosol jet printed pads for each sample. The advantages, disadvantages and full results of adhesion improvement method are discussed in the paper.

Nanoparticle based ink printed chip interconnections

This paper presents a research focused on Aerosol Jet interconnecting of SMD components to flexible substrates. Flexible printed electronics is becoming important fast growing market segment. Contacting technologies of the electronic components are well known for traditional electronics such as soldering, welding, conductive adhesive bonding, however in the expansion of direct printing technologies the new possibilities have raised. Without using of conductive adhesives the Aerosol Jet technology can be used for contacting. The interconnections were realized by silver nanoparticle ink. Two possible options were examined — direct interconnecting and interconnecting with dielectric blob. Issues of the Aerosol Jet interconnecting, used materials and measured data are discussed in the paper.

Comparison of copper and silver thick film on alumina substrates properties

This paper deals with comparison of copper (Thick Printed Copper) and silver thick films on alumina substrates properties. Thick film technology is used in many fields of electronic industry. Thick printed copper is a new prospective technology, which is used for power electronics substrate manufacturing. Comparison of adhesion, solderability and other properties of TPC technology and silver thick films are mentioned in this paper.

Comparison of the characteristics of PCB protective coatings

This article presents a research focused on printed circuit board (PCB) protective coatings as an option for cover the assembled PCBs and electronic device reliability improvement. The experiment with five different coatings is described in the article. For the experiment rigid substrate (FR-4) and flexible substrate (Kapton) were used. The protective coatings from acrylic, urethane, silicone and fluoropolymer materials were used. The differences in substrates and coatings has an effect on the insulation resistance which was measured by SIR test. The samples were exposed to accelerated aging tests — combined accelerated aging by temperature and humidity, and salt spray test. The advantages, disadvantages, comparison and results from measurement are discussed in this paper.

Shear Strength of Conductive Adhesive Joints on Rigid and Flexible Substrates Depending on Adhesive Quantity

Abstract This article deals with the impact of electrically conductive adhesive quantity on the shear strength of joints glued by adhesives “EPO-TEKⓇ H20S” and “MG8331S” on three types of substrates (FR-4, MELINEXⓇST504, DuPont™ PyraluxⓇAC). These joints were made by gluing chip resistors 1206, 0805 and 0603, with two curing profiles for each adhesive. Different thicknesses of stencil and reductions in the size of the hole in stencils were used for this experiment. These differences have an effect on the quantity of conductive adhesives which must be used on the samples. Samples were measured after the curing process by using a shear strength test applied by the device LabTest 3.030. This article presents the effects of different curing profiles, various types of substrates, and different quantities of adhesives on the mechanical strength of the joint.

Properties of temperature stable solder pastes

This article deals with the temperature stable solder pastes and the using of this pastes in a manufacturing process. The nineteen solder pastes were chosen at the start of the research and were compared. For the experiment four solder pastes (Loctite GC10, KOKI M406 ECO, AIM M8, Indium 8.9HF) with the best parameters in datasheets were chosen. In the experiment fourteen parameters were measured or monitored. All results were transformed on points and multiplied with significant coefficients. The overall results were calculated and the pastes with the highest point amount were recommended for production usage.