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Electronics Manufacturing Technology Symposium, 1998. IEMT-Europe 1998. Twenty-Second IEEE/CPMT International

Date 29-29 April 1998

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Displaying Results 1 - 25 of 28
  • Twenty Second IEEE/CPMT International Electronics Manufacturing Technology Symposium. IEMT-Europe 1998. Electronics Manufacturing and Development for Automotives (Cat. No.98CH36204)

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    Freely Available from IEEE
  • Practical production uses of SMT adhesives

    Page(s): 147 - 155
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    Adhesives are typically used in surface mount printed circuit board (PCB) assemblies to hold the passive (and sometimes active) components on to the bottom side of the board during wave soldering. The adhesive is used to bond the surface mount device (SMD) to the PCB, thus forming a joint between the SMD body and the solder resist or bare FR-4 board between the solder pads. This is necessary to avoid the displacement of components from their sites during high speed placement of passive components. Dispensing equipment must be able to dispense a precise consistent dot shape with different volumes as appropriate for different device sizes. After the SMD is placed, the wet adhesive must have sufficient “wet” or “green” strength to hold the SMD in position until cured. The hardening process must be fast and simple. The cured adhesive must then have sufficient strength to hold the SMD to the PCB during the solder wave operation. After soldering, the adhesive must not affect circuit operation in any way. Generally, the spacing between the component pads dictates the maximum allowable adhesive dot diameter that can be dispensed between the pads. Typically, the adhesive dot diameter is 2/3 of the pad spacing. Once the allowable adhesive dot diameter has been determined, the appropriate nozzle can be selected. A dual dot nozzle or single dot nozzle should be chosen at this time View full abstract»

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  • Soldered flip chip IC's in automotive applications

    Page(s): 27 - 30
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    During recent years, we have accumulated a great deal of experience with high volume production of soldered flip-chips in small modules for automotive applications. We have processed more than 20 million flip chips with excellent results in terms of processing and reliability. There are several advantages for using hybrid flip chip modules for these applications. The reasons are given in this paper. Problems related to printing, mounting and soldering had to be solved, especially with respect to throughput. We therefore decided to screen print and place with a high speed placer, though stencils and fine pitch placers give higher accuracies. Nevertheless, we reached 2000 thermal cycles from -40°C to +140°C with this configuration without test failures; factory fall-off is less than 10 ppm View full abstract»

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  • Prospective developments in automotive instrumentation

    Page(s): 10 - 15
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    In this paper, we review the status of automotive instrumentation and consider future developments in emerging display technologies for use in automotive displays. In particular, we focus on the various ways in which conventional display technologies can be effectively used to replace a profusion of ancillary instruments and a number of primary indicator functions required by instrumentation engineers to overcome demands for increased information content. We take the fundamental characteristics of various prominent display technologies into account and try to identify where they may provide a suitable design solution for automotive instrumentation. We discuss the use of active matrix liquid crystal displays (AMLCDs), electrically controlled birefringent color LCDs, implementation of improved drive schemes for higher contrast ratios such as multi-line addressing, the use of reflective-only displays, and techniques for brightness enhancement using high-efficiency filters. Besides LCD-based displays, we also consider other alternative display technologies which may have automotive applications in the foreseeable future and how may they be applied. Such technologies include VFD, LED, EL, FED, LCD light valves and head-up displays (HUDs), which have the potential to introduce instrumentation which follows driver eye movement. Finally, we address issues relating to the manufacture and integration of displays for automotive instrumentation to include cost, reliability, weight, and footprint by adopting advanced packaging technologies such as flip-chip-on-glass (FCOG) View full abstract»

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  • Thermal expansion and thermal conductivity of continuous carbon fibre reinforced copper matrix composites

    Page(s): 104 - 108
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    Carbon fibre reinforced copper matrix composites with adequate quality are promising materials in applications where heat transport plays an important role, e.g. as heat sinks for the electronics industry. Apart from good thermal conductivity, a low coefficient of thermal expansion is also important. In order to produce the material in an economical manner, the approach here used continuous PAN-type carbon fibres (Torayca T300). The fibres have been continuously copper coated, and unidirectional and cross-ply samples have been produced by diffusion bonding. The coefficient of thermal expansion and thermal conductivity of the material have been investigated. Thermophysical properties have been measured in both longitudinal and transverse directions to the fibre orientation. The results showed that the cross-ply Cu-Cf MMC produced from the Torayca T300 fibres may be a suitable candidate for heat sinks because of its good thermophysical properties, e.g. in-plane thermal conductivity (≈145 W/m.K), through-thickness conductivity (≈50 W/m.K), low density (≈5 g/cm 3) and the low coefficient of thermal expansion (8-9×10 -6 K-1) View full abstract»

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  • Multilayer alumina substrates for ECU [automotive electronics]

    Page(s): 109 - 112
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    Alumina multilayer ceramic substrates (MLCS) offer high reliability for use in the automotive field in terms of significant size reduction, thermal durability, high heat dissipation, rigidity, and extended practical application. The work described in this paper summarizes the achievements of design significance of multilayer cofired alumina. The combination of the inherited superior design and processing rules brings forth the realization of miniaturization of about 30% in terms of size (area) compared to the use of conventional glass epoxy substrates. In addition, the thermal conductivity of alumina, 18 W/mK, which is almost 10 times that of glass ceramics (LTCC), and its inherited mechanical/thermal durability enables the substrate to be attached directly to the engine with good heat dissipation. We performed various reliability tests for the substrates for 3000 hours/3000 cycles without any defects. Additional alumina multilayer technology applications for automotive electronics besides electronic control units (ECU) are mentioned in this paper View full abstract»

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  • Investigations of Au-Sn alloys on different end-metallizations for high temperature applications [solders]

    Page(s): 156 - 165
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    Au-Sn solder is becoming increasingly important in the field of microelectronic packaging. For high temperature and fluxless applications in particular, for example in optoelectronics, Au-Sn solder bumps are used. The Au-Sn solders come in contact with different end-metallization systems such as nickel, platinum or palladium used as underbump-metallization. Information about the Au-Ni-Sn, Au-Pd-Sn and Au-Pt-Sn ternary systems in terms of metallurgical fundamentals are very important for understanding and controlling the technological processes. This knowledge is the base for investigations of reliability, phase formations, growth and stability, diffusion mechanisms and diffusion pathways. This paper summarizes the work done on different Au-Ni-Sn, Au-Pd-Sn and Au-Pt-Sn alloys with maximum 20 at.% Ni, Pd and Pt contents, and investigations on diffusion and interface reactions of Au-Sn solders on Ni, Pd and Pt. Isothermal sections of the solid state are introduced. The presence of unknown Au-Ni-Sn and Au-Pd-Sn phases in the tie-triangle is discussed. Results of diffusion investigations and interface reactions are shown View full abstract»

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  • Dispensing flip chip underfill process problems and solutions

    Page(s): 119 - 124
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    Although flip chip is not a new technology, over the last few years we have seen this low cost interconnect solution applied to substrates other than ceramic. It is now increasingly widespread that bare die and flip chip are mounted on FR4 and even flex substrates for low cost manufacturing of advanced electronics such as PDAs, pagers and mobile phones. With the use of these new substrates has arisen the need to “underfill” the die after reflow. This paper details the different hardware requirements and the process parameters involved and their effect on the final results obtained. Understanding each parameter and the controls that are required in a production environment is the key to correct process implementation View full abstract»

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  • Development tendencies in automotive electronics

    Page(s): 5 - 9
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    Increased customer demand for state-of-the-art vehicles means that the vehicle manufacturer must integrate new, more complex electronic functions. Therefore, an increasing number of systems in passenger cars are electronically-controlled, and the complexity of existing systems increases out of all proportion. Electronics is beginning to determine functions and value, and has therefore become a considerable factor with regard to competitiveness View full abstract»

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  • Development of 3-dimensional memory module using anisotropic conductive adhesive films

    Page(s): 31 - 37
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    The memory modules used in most modern electronic equipment, ranging from portable electronic information devices to computers to ATM electronic switching systems, are facing not only greater demands for smaller size and lower cost, but also new demands for larger memory capacity. To satisfy such needs, NEC has developed a small-size, low-cost, large-capacity memory module, which consists of three-dimensionally stacked memories by use of anisotropic conductive adhesive films. The memory module comprises stack memories consisting of 3D mounted multiple memory ICs and a single glass epoxy substrate on which multiple stack memories are mounted. A stack memory consists of two single memories, a spacer substrate, and external connection terminals. A single memory consists of a memory IC mounted on a glass epoxy substrate. The two single memories are electrically connected to each other by use of a spacer substrate and anisotropic conductive film (ACF). The external connection terminals, which consist of copper core-filled solder balls, are then mounted on the single memory in the lower stage of the stack memory. The method used for radiation of the heat generated by stacking was verified by simulation. It became clear from the simulation results that the method did not present any problem for the memory ICs used at this time. It also became clear that the method of mounting a heat sink for high heat generating ICs in the future could be a promising solution. The method, subjected to all types of reliability tests, revealed no problem at all View full abstract»

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  • Results of assembly and reliability investigation of an MCM-L for an automotive application: electronic control unit

    Page(s): 63 - 69
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    In the last year, MCMs have changed the view of electronic manufacturing due to novel functions. MCMs offer an attractive alternative to packaged components, as they increase packaging density and improve the reliability of electronic functions in a harsh environment. MCMs can increase manufacturability and, due to the use of low cost materials, they can save space, volume and weight in order to decrease overall costs. This paper shows the results of reliability tests carried out on test vehicles to optimise the manufacturing process. As base substrate materials, high Tg FR-4 and BT-epoxy was used to process the VLSIs on the MCM-L. The assembly was done using chip-on-board technology with chip-and-wire and flip-chip technology, showing the high performance of both methods. The paper presents current improvements to the substrate manufacturing process and fine pitch flip-chip bonding process. Different encapsulation technologies (glob top, underfilling, metal lid) are used to optimise reliability and media resistance for automotive requirements of harsh environment conditions for under-the-hood applications. Finally, the best technologies and processes, in terms of reliability performance and cost, have been selected to build the electrical demonstrator: an electronic control unit (ECU), which is briefly described View full abstract»

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  • Thermophysical properties and microstructure of short carbon fibre reinforced Cu-matrix composites made by electroless copper coating or powder metallurgical route respectively

    Page(s): 98 - 103
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    C fibre reinforced Cu matrix composites have the interesting properties of Cu, i.e. thermal and electrical conductivities, but the properties of the C fibre, i.e. small CTE, dominate mechanical behaviour. As desired composite properties can be obtained by selecting the amount and type of C fibres, it is suitable for electronic applications such as special heat sinks. Cu matrix composites with high conducting short fibres are a promising research field. Short C fibre reinforced Cu composites were made by hot-pressing of Cu coated C fibres chopped into different lengths (60 μm-2 mm). By using electroless Cu coating-based production, a good fibre distribution in the matrix and good interfacial contact were obtained. The fibre length distribution strongly influences composite properties. During hot pressing, the C fibres take on a preferred orientation in a plane perpendicular to the hot pressing direction. Within this plane, fibre orientation is random. C fibre volume content was varied in a 38-64 vol.% range. The composite microstructures were studied by SEM and optical microscopy. Measured thermal conductivity and CTE were compared with microstructural results and results from mathematical models. The composites have thermal conductivity of about 250-300 W/mK in two dimensions and about 140 W/mK in the third dimension. The CTE can be tailored in a range of 4-10 ppm/K by changing the C fibre content. The relatively low density of 4-6 g/cm 3 is also important where weight reduction is desired. The results are compared with composites produced by powder metallurgical methods and those made with low conducting short C fibres View full abstract»

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  • Advanced MCM-D micro-processor module for ATM wide-area network switching systems

    Page(s): 21 - 26
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    This paper describes an advanced MCM-D microprocessor module and its high-performance cooling technologies for an ATM-WAN (wide area network) switching system. The MCM-D is fabricated on 2 Si-substrates using the stacking RAM technique to reduce module size. The MCM has 4-layer Si substrates, a microprocessor LSI, 4 ASIC-LSIs, 12 high-speed SRAMs, an FPGA and bus-driver ICs. By using the stacking RAM technique, MCM-D size was reduced to 63 mm×85 mm. This is 14% of the assembly area (200 mm×200 mm) of a conventional circuit using conventional packaging technologies. The MCM-D was mounted on an ATM line interface circuit board, and realized 25 MHz microprocessor functions with high-speed (access time 25 ns) and large-capacity (4 MBytes) SRAM cache and ATM line interface circuit functions in an ATM-WAN switching system. The line interface circuit board-mounted MCM-D has a high-performance cooling architecture without fin structure. The MCM-D module is mounted on a sub-board and has thermal contact to the main board through a rubber spacer with low thermal resistance. By using this high-performance cooling architecture, the MCM-D microprocessor module and the ATM line interface circuit board operate under conventional forced air cooling conditions without a fin structure. This MCM technology and high-performance cooling technology can be applied to ATM-WAN switching systems and future B-ISDN ATM switching systems View full abstract»

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  • Low-cost direct chip attach: comparison of SMD compatible FC soldering with anisotropically conductive adhesive FC bonding

    Page(s): 49 - 54
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    Small modules based on laminate substrates are often used as a functional subunit in electronic applications. Currently, most are made by the chip and wire technique to fulfil size reduction requirements. Low cost flip-chip technology is one of the most promising approaches for further cost and size reduction. In this paper, a special car radio submodule is chosen as an example. We compare an SMD compatible FC soldering process using eutectic solder bumps and underfilling with an anisotropically conductive adhesive (ACA) FC bonding process using tape or paste materials. For FC soldering, an electroless, maskless Ni/Au plating for under bump metallization (UBM) was chosen. The solder deposition is by stencil printing, while other cost efficient deposition techniques have been observed. The FC assembly is integrated into a standard SMD line. Different underfill methods for quick underfilling are shown, and failure mechanisms and lifetime predictions of assembled flip chips are demonstrated. For ACA-FC bonding, electroless Ni/Au bumping is also used. An assembly process for ACAs using a semi-automatic FC bonder is developed. In order to reduce mounting time, the ACA has been precured. Aspects of different process flows, including ACA deposition techniques, tape and paste adhesives and filler materials, are discussed. The influence of high current, climate, and thermal cycling on the contact resistance and low frequency noise spectrum is shown. In summary, we describe the benefits and disadvantages of both techniques and discuss the potential for further developments and applications View full abstract»

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  • A new screen printing process with important potential automotive applications

    Page(s): 125 - 130
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    Potential automotive application-specific process developments are outlined which use thick polymer stencils that allow printing of a range of different height deposits at the same time. This paper looks at the use of this process for assembly in four areas: (a) double sided SMT assembly of designs with through-hole components; (b) double sided designs with surface mount components with a single reflow oven pass; (c) replacement of `pin-dip' adhesive application, so that newer, smaller SMT components can be repeatedly and reliably assembled; (d) a simplified, in-line compatible, underfill assembly sequence which utilises screen printing only View full abstract»

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  • Low cost, high performance, high volume heatsinks

    Page(s): 113 - 118
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    Higher-powered electronics are being integrated into automobiles rapidly. With these electronics comes the problem of how to cool this equipment economically. Heat sink costs have not benefited nor adapted to the high volume nature of automotive electronics. Specially shaped heat sinks are much more efficient for a given size than the aluminum extrusion-based ones most prevalently used in automobiles. However, machining costs preclude specially shaped heat sink use in most automotive applications. High purity extruded aluminum has always been a good heat sink material for electronic components. Casting aluminum to create more efficient and useful shapes has a severe penalty in thermal conductivity due to the impurities necessary for casting. Porosity is another significant factor which lowers thermal conductivity in both die and hand cast aluminum. This paper gives show a new heat sink design and material process that allows porosity-free low cost heat sinks to be diecast into complicated 3D shapes. A cost and performance analysis comparing different high volume heat sink manufacturing methods, die cost, and per piece cost are examined for various commercial copper-based, zinc, zinc-aluminum, and aluminum die casting materials. Additionally, the paper shows where the automotive industry can benefit from these technologies and where they may not be as appropriate View full abstract»

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  • Charge build-up and its reduction in plasma cleaning process

    Page(s): 92 - 97
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    Charge build-up in the plasma cleaning process has been investigated from the viewpoints of plasma uniformity, gas species and pressure, plasma exposure time, anode-cathode distance and substrate (circuit board) configuration. The spatial distribution of plasma parameters in plasma cleaning was diagnosed using a Langmuir probe. The charge build-up was evaluated using MNOS capacitors and MOS capacitors. Gases such as Ar, Ar-H2, Xe and O2 have been investigated. It has been found that the spatial distribution of plasma parameters is uniform, and that the charge build-up in plasma cleaning is negligibly small with regard to test chips placed without substrates. Use of substrates was found to increase the amount of charge build-up. Charge build-up was found to depend on the size, material and structure of the substrate. It was found that plasma cleaning with substrates with a conductive surface film such as a plated gold film resulted in considerable charge build-up. We found that use of an insulator mask or insulating die-bonding paste was very effective for charge build-up minimization View full abstract»

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  • FEM analysis of flip-chip type BGA

    Page(s): 131 - 136
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    A three-dimensional FEM (finite element method) analysis was performed on a flip-chip type BGA (ball grid array), and the resulting maximum equivalent plastic strain range (MEPSR) was used to determine the optimum material and structure for such packages. As a result, we were able to confirm the substantial influence of the combination of various materials, and structural parameters upon the package thermal fatigue life, and its nature. This also allowed us to optimize the material elements, an important parameter in package design, and the package structure View full abstract»

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  • Contact mask technique for laser structuring of 3-D MID

    Page(s): 38 - 43
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    Molded interconnect devices (MID) are promising polymer components for many industrial applications to make complex functional components containing circuits possible, and to avoid material and production costs. Current examples in the automotive field are a car dash board and a rear stop light. For suitable large scale production technologies for complex 3D MIDs, development of new manufacturing processes is essential. Different technologies are used to generate circuit patterns on the substrate by photoimaging. The geometrical information can be transformed by using different mask technologies. Besides the common mask projection technique, a contact mask which contains the circuit geometry is also suitable. The circuits are therefore generated in original scale by IR laser radiation on a polyvinyl chloride (PVC) sheet. The blackened polymer is nontransparent for the UV radiation of common UV lamps and excimer lasers in particular, used for imaging of photosensitive resists. For three-dimensional masks, the sheet is formed by a deep drawing process View full abstract»

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  • VSPATM: a new family of low cost three dimensional semiconductor packages for single and multiple chip modules

    Page(s): 44 - 48
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    A new family of semiconductor packages, referred to as VSPATM , is described which combines unique 3D design features and materials technology selection to produce superior electrical, thermal and mechanical performance for both single and multiple chip modules. These packages are readily scalable to accommodate a wide variety of footprint, shape, I/O (up to 1000) and bandwidth requirements at very low cost ($0.01). The unique design and fabrication method eliminates the die leadframe, allowing a smaller footprint, relaxed lead pitch, and robust leads with improved coplanarity. The I/O pins are a constant regardless of the package frame size, which provides a low inductance path from die to PCB. The peripheral lead structure allows for visual inspection and ease of rework. The die attaches in a flip chip manner to a metallic plate, an integral part of the package, providing a direct thermal path to ambient or cooling devices. The 3D stacking of the leads results in significant size reduction, low inductance paths, with the pin design providing reduced package parasitics and allowing resonance free operation up to 3.5 GHz. Techniques for 3D chip stacking are described as well as environmental test results, standard activity, and novel heatsink designs. A liquid crystal polymer frame provides excellent stability with a 335°C melt point, and allows for tolerances of less than 1 mil to be held for pin alignment and coplanarity in high volume manufacturing environments View full abstract»

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  • Design for environment in automotive electronic design

    Page(s): 1 - 4
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    The increasing number of automotive applications is one of the driving forces behind the miniaturization of electronics. Since miniaturization means less use of resources, this trend seems to be inherently benign for the environment. Adverse effects overlay this simple truth. The overall amount of electronics in a car multiplies. The complexity and closeness of nonseparable compounds increase. The decentralization of automotive electronics is a major handicap for recycling at the end of car lifetime. This aspect becomes increasingly important, since car producers are forced by the government (e.g. since April 1st 1998 in Germany) to take back old cars. Similar to the information and communications industry, it can be expected that car producers ask their suppliers about the environmental aspects of their products. In this paper, an overview of international tendencies in design for environment are given View full abstract»

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  • Alternative solders for flip chip applications in the automotive environment

    Page(s): 82 - 91
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    In addition to Pb toxicity, there are other problems with SnPb solders. In automotive applications, where solder joints are subjected to thermal cycles, severe vibrations, sustained temperatures up to 150°C and peak temperatures of 180°C, the critical failure mode of eutectic SnPb solder in assemblies is bump fatigue. For flip chip technology, induced thermal stresses and strains in solder joints are very hazardous. This paper presents a flip chip process based on electroless Ni/Au bumping and stencil printing of solder paste on wafers. Chemical nickel plating combined with solder printing is a very flexible and cost effective bumping method. The basic process steps and key aspects of this technology are described in detail. Experimental results for an ultra fine pitch printing technique on wafers are shown, and reflowed solder bumps are characterized for uniformity and strength. In comparison to eutectic SnPb, SnBiCu, SnAg, SnCu, and AuSn solder alloys are selected and investigated. The alloys are compared for flip chip technology applicability, microstructure and phase compositions are presented. Microstructure coarsening and phase growth after thermal aging are also investigated. In order to investigate substrate material CTE effects on reliability, flip chip assembly was performed on low temperature cofired ceramic (LTCC) and FR-4 substrates. The flip chip joint quality was investigated by metallurgical cross sections and electrical and mechanical measurements. Finally, the reliability results of these joints after thermal cycling with and without underfill on both types of substrate materials are presented View full abstract»

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  • MID in the automotive industry-potentials, benefits and applications

    Page(s): 76 - 81
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    Molded interconnect device (MID) technology integrates electrical and mechanical functions into a single molded part. A variety of methods is available for manufacturing MIDs. Depending on the application, the use of MID technology allows more than 20% in cost savings over conventional technologies, as proven by several examples. MIDs boast a wide field of applications in an automobile and have been sucessfully used in several cases View full abstract»

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  • Reducing electro-magnetic radiations with a multi chip module

    Page(s): 16 - 20
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    The amount of electronic equipment loaded in cars is increasing. All parts of the vehicle are now driven by electronics, such as the engine control unit which manages the engine, or clutch and gear box systems which manage the car chassis, or, more recently, the alarm and navigation systems which manage the car body. Each generation of electronic equipment must be increasingly powerful, but at the same time the size must be reduced. Higher clock rates and data exchanges are good solutions for increased electronic equipment performance, but are bad for electromagnetic radiation. The use of multichip modules, with dice directly bonded to a small PCB, mixes the advantages of reduced hardware size for equivalent performance, a single package for several dice, and also to reduce the radiated electromagnetic field. This paper presents the differences in radiated emission levels between a microcontroller alone and a MCM using the same microcontroller with RAM and flash memory. The methodology used for the comparison according the American SAE 1752/3 standard is described. The test method used a TEM cell specially designed for component emission tests in the 150 kHz to 1000 MHz range. An analysis of the results allows identification of the different noise origins, such as the device core, clock systems and bus distribution. This also allows quantification of the gain of around 10 dB on radiated emission levels up to 1 GHz View full abstract»

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  • New methods in accelerated reliability testing of electronic components for automotives under field conditions

    Page(s): 143 - 146
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    The reliability of components and circuits is normally determined by standardized methods. Test programs with special parameters must be fixed in contracts between supplier and customer. In order to save time, accelerated tests are used. The results of these tests can only be statements of “passed” or “failed”. Problems arise from the fact that failure rates of components, especially in electronics, become ever smaller. The acceleration factors for the degradation processes involved are often unknown. Overstressing must be avoided. No information is given about such parameters as expected lifetime. FEM methods are promising but still suffer from the lack of knowledge of degradation dependent physical data. Some new developments deal with accelerated testing under field conditions using degradation kinetics. Mathematical models for the active degradation processes are needed. Using high precision measurements, one can obtain experimental data for fitting procedures and for the calculation of reliability parameters. The paper gives some ideas in this area View full abstract»

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