Search results1 – 10 of over 1000
Plasma chemistry is employed almost exclusively for etching, cleaning and deposition processes in semiconductor device fabrication technology. As a natural expansion of…
Plasma chemistry is employed almost exclusively for etching, cleaning and deposition processes in semiconductor device fabrication technology. As a natural expansion of this successful technique, attention has been directed at similar processes for thick film ceramic, thin film hybrid and more generally printed circuit board electronic assemblies. This paper discusses a variety of applications, some established and some experimental, where plasma is offering the benefits which semiconductor engineers have enjoyed for many years. Such applications include general organic removal, i.e., flux residues, finger print contamination and the removal/reduction of oxides and glass on thick film conductors to promote improvements in solderability and wire bondability.
I was an invited speaker to the ISHM‐Benelux meeting. As I arrived early, I also sat in on the committee meeting as an observer. Jos B. Peeters was the outgoing president…
I was an invited speaker to the ISHM‐Benelux meeting. As I arrived early, I also sat in on the committee meeting as an observer. Jos B. Peeters was the outgoing president and the incoming committee was widened to about 15 members compared with the previous 6. Following the unanimous election of all those nominated, the committee reconvened and elected Mr Kwikkers as the new president of ISHM‐Benelux. He is a professor at the Technische Hogeschole in Delft.
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.
As the speed, density, power dissipation, and overall performance of semiconductor chips continue to improve, electronic equipment designers are finding that their ability…
As the speed, density, power dissipation, and overall performance of semiconductor chips continue to improve, electronic equipment designers are finding that their ability to utilise new, high performance ICs is limited by the electrical performance, cost and turnaround time associated with the higher levels of packaging and interconnection. With the evolution of silicon foundries, CAD systems, logic array and standard cell technology, the designer now has the ability to develop and implement custom IC functions rapidly at a fraction of the cost and time associated with full custom IC development. The driving force for this evolution is the need for reduction of product development time and cost. As electronic product life cycles continue to decrease, so must the development time. Although the need to reduce component development times has been acted on first by the semiconductor manufacturers, suppliers of packaging and interconnection components are also feeling the need to provide customised designs rapidly and at low cost. Unilayer II is a discrete wire circuit board technology with a wiring density capability approximating that of multilayer printed wiring boards. However, since the wiring is defined in software and implemented on a numerically controlled wiring machine, the time and cost associated with development, and also with wiring changes, is greatly reduced. This paper presents the results of extensive electrical testing performed to characterise the electrical performance of the discrete wire Unilayer II transmission lines. Characteristic impedance, propagation velocity, capacitance, inductance, and crosstalk are discussed in detail.
Summarizes the different techniques for the removal of conformal coatings from printed circuit boards and other electronic assemblies. Addresses each of the four techniques for the removal of conformal coating (thermal, mechanical, chemical and abrasive), along with how they work with each type of conformal coating (urethane, acrylic, silicone, epoxy, parylene and UV curable coatings). Also provides summaries for the removal times and clean up for each technique.
This paper focuses on the renewed interest in the use of condensation, or vapour‐phase, soldering in lead‐free surface mount assembly soldering and notes also the…
This paper focuses on the renewed interest in the use of condensation, or vapour‐phase, soldering in lead‐free surface mount assembly soldering and notes also the corresponding legislation, which will preclude the use of lead‐based solders in most applications by 2006. The process is once again becoming popular, because of the absolute control of soldering temperature, and because high‐quality batch and in‐line equipment is now available. It notes that condensation heating with perfluorocarbon liquids and present well‐designed equipment can be used not only in the mass‐assembly of electronic circuit boards, but also for a large variety of other heating tasks in many industries.
The reliability of 0.5 mm pitch, 32‐pin thin small outline package (TSOP) solder joints has been studied by experimental temperature cycling and a cost‐effective 3‐D…
The reliability of 0.5 mm pitch, 32‐pin thin small outline package (TSOP) solder joints has been studied by experimental temperature cycling and a cost‐effective 3‐D non‐linear finite element analysis. Temperature cycling results have been presented as a Weibull distribution, and an acceleration factor has been established for predicting the failure rate at operating conditions. Thermal fatigue life of the corner solder joints has been estimated based on the calculated plastic strain, Coffin‐Manson law and isothermal fatigue data on solders. A correlation between the experimental and analytical results has also been made. Furthermore, failure analysis of the solder joints has been performed using scanning electron microscopy (SEM) and an optical method. Finally, a quantitative comparison between the Type‐I and Type‐II TSOP solder joints has been presented.
The effect of heat‐spreader sizes on the temperature distribution, thermal resistance, and cooling power of a set of cost‐effective cavity‐down plastic ball grid array…
The effect of heat‐spreader sizes on the temperature distribution, thermal resistance, and cooling power of a set of cost‐effective cavity‐down plastic ball grid array (PBGA) packages assembled on an FR‐4 epoxy glass printed circuit board (PCB) is presented. The sizes of these packages are 35 × 35mm and 40 × 40mm and with four and five rows of solder balls.
The purpose of this paper is to evaluate the mechanical properties of glass fibre reinforced epoxy composites modified with amine‐terminated poly (ethylene glycol…
The purpose of this paper is to evaluate the mechanical properties of glass fibre reinforced epoxy composites modified with amine‐terminated poly (ethylene glycol) benzoate (ATPEGB) along with their thermal stability.
ATPEGB prepared from poly (ethylene glycol) (PEG) of different molecular weights (200, 400, 600, 4,000 and 20,000) were used as modifiers for glass fibre epoxy composite here. For toughening, 12.5 parts per hundred grams (phr) of epoxy resin of each ATPEGB was added to epoxy and pre‐reacted with it. The impact, tensile and flexural strengths of modified and unmodified composite were characterised and compared for each ATPEGB.
Modified resin displayed a significant improvement in fracture toughness with glass fibre over unmodified epoxy. The modification caused the formation of oligomer domains having relatively round shapes in the matrix. These oligomer domains led to improved strength and toughness due mainly to the “rubber toughening” effect in the brittle epoxy matrix. The optimum results were obtained for composite modified with ATPEGB‐2 prepared from PEG of molecular weight 400.
In the present context, only 12.5 phr concentration of each ATPEGB was used to modify composite and the composites were made sing three layers of glass fibre. Besides, modification could also be done using other concentrations and more layers of glass fibre could also be used to make composite.
The method for enhancing toughness of epoxy glass fibre composite was novel and finds numerous applications as surface coatings, casting and adhesive onto an intricate structure, etc.