This presentation is a quick overview of ceramic chip capacitors. Subjects covered are: basic structure, manufacturing process, specifications, and basic characteristics. Capacitors are devices that store energy in the form of an electric field. They can also be used to filter signals of different frequencies.
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Metal Oxide Varistor Degradation
The invention relates to the trimming of a resistor or resistors, suitable for use at any level of the manufacturer-to-user chain. More specifically, it relates to trimming by resistive heating using electric current in the resistor itself or in an adjacent resistor.
The trimming adjustment of resistors is a widely used procedure in the manufacture of microelectronics and electronic components, and in common design of user circuits, especially where precision calibration is desired. In principle, one trims the resistor until an observable local or global circuit parameter reaches a desired value.
Resistor trimming is widespread in both manufacturing of a variety of components and instruments, and in the user community. Several methods exist for trimming resistors, applicable at various levels of the manufacturer-to-user chain, including laser-trimming, electrical trimming, trimming by reconfiguration of resistor networks using fuses, and the use of trimpots potentiometers having variable numbers of resistive turns.
Electro-thermal trimming phenomena have been observed by several authors, for the trimming of a variety of resistor materials. In their formulation, the resistance behavior is found to be highly non-linear, with little or no change in resistance for low power dissipation below a certain threshold , and dramatically increased instability above a certain threshold.
Also, research at Motorola by D. Feldbaumer, J. The thermal instability, unstable resistance variation with temperature of polysilicon resistors located on micro-machined platform suspended over cavities, is known Canadian Microelectronics Corporation Report IC September ; and O.
Grudin, R. Marinescu, L. Landsberger, D. Cheeke, M. Engineering, , Vol. It is known that, for a resistance element on a micro-platform, the resistance could be increased or decreased depending on the power applied through that resistance element.
This is usually considered to be a disadvantage for the use of polysilicon for resistive elements where stability is important. This present invention concerns the use of this instability or any similar threshold-dependent instability in resistive materials , to overcome any of a group of several obstacles present in the aggregate of the prior art.
In particular, the material should be stable below a certain threshold of temperature or power dissipation, and relatively less stable above such a threshold, such that its resistance can be modified. There exists electrical trimming of metal resistors based on inducing electro-migration in the resistive elements by pulsing high currents U. This method relies on very high current density to cause the electro-migration.
There exists electrical trimming based on thermally-induced changes in resistivity of polysilicon resistors residing on a substrate U. Babcock, V. Mercier, C. Electron Devices, , vol. This method relies on the application of highly dissipated power such as several watts , to sufficiently heat the resistors while they are on the substrate which effectively acts as a heat-sink. This in turn requires high voltage and brings the danger of damage from electrostatic discharge ESD.
Arguably in large part to get around this problem, Motorola invented thermal trimming of a functional resistor by an auxiliary resistor which is electrically-isolated from the functional resistor. This allows functional trimming to set a parameter of a larger circuit U. This also allows the trimming of resistors having high resistance values, without extra constraints on the heater resistor. The Motorola invention involves placing the resistors one over the other, separated by a very thin electrically-insulating film.
This configuration is required principally because the two resistors are situated on the substrate, which acts as a heat sink. Thus, a substantial amount of power is required to be dissipated to attain the trimming temperature.
Consequently, the one-over-the-other configuration is preferred in the prior art, in order to maximize the heat transferred from the heater-resistor to the functional-resistor. Any other configuration, such as side-by-side and made from the same deposited layer, would require much higher power-dissipation in the heater-resistor, which in turn would require a higher supply voltage and would unduly heat the substrate.
It should be noted that the substantial power dissipated in the heater resistor must be conducted away through the insulating oxide, functional resistor, and other surrounding layers and devices. Volklein and H. Microelectromechanical Systems, Vol. Tai and R. Swart and A. Micro-platforms with embedded resistive elements are commonly seen in micro-sensor, micro-actuator and micro-electromechanical systems MEMS literature since or earlier e.
Choi and K. ED, No. The concept of using a resistive heater to heat an entire suspended micro-platform or microstructure is also well-known in the literature for at least approximately a decade C. Mastrangelo, J. Yeh, R. Swart, and A. Wessel, M. Parameswaran, R. Frindt, and R. Parameswaran, A. Robinson, Lj. Ristic, K. Chau, and W. University of Michigan has patented U. Thermal trimming of a thermo-anemometer-type of sensor such as a thermal accelerometer is known U.
This procedure is not reversible, and can be used only at the manufacturing stage not practical for user- or field-trimming.
The method involves calibration steps wherein the resistor is heated up to a predetermined temperature T , then the T-induced resistance drift is measured, then the structure is laser-trimmed to minimize net TCR of the combined resistor, and then the process is repeated until the TCR is reduced to the desired level. The inclusion of trimmable resistors in certain devices and applications has also been considered in prior inventions U.
There is a need for highly accurate trimming that can exceed the accuracy achieved by laser trimming and does not require special equipment such as powerful lasers.
Accordingly, an object of the present invention is to perform effective trimming of functional resistors made from unstable material, wherein the trimming behavior depends sensitively on temperature above a certain threshold, by obtaining a temperature relatively constant with time in the targeted element, and by obtaining a relatively flat spatial temperature profile in the targeted element. It is also an object of the present invention to independently trim functional elements, such as resistors, while maintaining them in close thermal contact.
It is also an object of the present invention to reduce the amount of power needed to accomplish trimming. It is also an object of the present invention to trim a functional element, such as a resistor, wherein a desired output signal depends critically on the interactive response of at least two functional independently trimmable elements.
According to a first broad aspect of the present invention, there is provided a method for trimming a functional resistor, the method comprising: placing a plurality of thermally-trimmable functional resistors on a substrate; and subjecting a portion of the substrate to a heat pulse such that a resistance value of one of said plurality of functional resistors is trimmed while a resistance value of remaining ones of said plurality of functional resistors remains substantially untrimmed.
Preferably, a thermally-isolated micro-platform is provided on the substrate and the plurality of thermally-trimmable functional resistors are placed on the thermally-isolated micro-platform. Preferably, pulse-heating is intended to heat a sub-region of the thermally-isolated plate. Here, it is intended for the heat dissipation or the bulk of the heat dissipation to be localized within a relatively small portion containing the heat-targeted region or regions, which may be areas or volumes of a thermally-isolated plate without affecting other elements on the plate.
Four types of pulses steady-state square pulse, quasi-static square pulse, dynamic square pulse, and dynamic shaped pulse are to be used in this particular mode heating a sub-region of the thermally-isolated plate.
In the sub-region on substrate, it is intended for the heat dissipation or the bulk of the heat dissipation to be localized within a sub-region containing the heat-targeted region of a device, where that sub-region is simply located on a substrate, usually a semiconductor substrate. The heat-targeted region may be directly on the substrate, or supported or separated from the main substrate by thin films, which may be insulating. In the thermally-isolated plate, it is intended for the heat dissipation or the bulk of the heat dissipation to be localized within a relatively thermally-isolated plate containing the heat-targeted region.
The plate is relatively well thermally isolated from a main substrate, usually a semiconductor substrate. One way to accomplish this thermal isolation is to make the plate suspended over a cavity in the substrate. The plate may often be composed of various layers, such as insulators or conductors or semiconductors, as long as the overall thermal isolation is substantial. Essentially, all three heat localization modes can be used with a dynamic shaped pulse. According to a second broad aspect of the present invention, there is provided a method for providing and trimming a circuit, the method comprising: placing at least two resistive elements with non-zero temperature induced drift on a substrate to be thermally isolated, such that said at least two resistive elements are subjected to a substantially same operating environment, at least one of said at least two resistive elements being thermally trimmable; trimming said at least one resistive element to trim said circuit by thermal cycling; connecting said at least two resistive elements together in said circuit in a manner to compensate for said operating environment; wherein heat generated during operation on the at least one micro-platform is distributed among said at least two resistive elements such that temperature drift is substantially compensated.
Preferably, at least one thermally-isolated micro-platform is provided and the at-least two resistive elements are placed on the thermally-isolated micro-platform.
According to a third broad aspect of the present invention, there is provided a method for trimming a functional resistor, the method comprising: placing a functional resistor on a substrate; subjecting said functional resistor to a heat source having a power dissipation geometry adapted to obtain a substantially constant temperature distribution across said functional resistor when a temperature of said functional resistor is raised for trimming purposes; and trimming said functional resistor using at least one heat pulse.
Preferably, a thermally-isolated micro-platform is provided on the substrate and the functional resistor is placed on the thermally-isolated micro-platform. According to a fourth broad aspect of the present invention, there is provided a circuit for trimming a functional resistor, the circuit comprising: a thermally-isolated micro-platform on a substrate; a plurality of functional resistors spaced apart on the thermally-isolated micro-platform; and trimming circuitry for subjecting a portion of the thermally-isolated micro-platform to heat pulses such that a resistance value of one of said plurality of functional resistors is trimmed while a resistance value of remaining ones of said plurality of functional resistors remains substantially untrimmed.
According to a sixth broad aspect of the present invention, there is provided a circuit for trimming a functional resistor, the circuit comprising: a thermally-isolated micro-platform on a substrate; a functional resistor on said thermally-isolated micro-platform subject to a heat source having a power dissipation geometry adapted to obtain a substantially constant temperature distribution across said functional resistor when a temperature of said functional resistor is raised for trimming purposes; and trimming circuitry for trimming the functional resistor.
According to a seventh broad aspect of the present invention, there is provided a method for calculating a temperature coefficient of resistance of a functional resistor, the method comprising: placing a functional resistor on a substrate to be thermally isolated; heating said functional resistor; measuring a resistance value of said functional resistor at ambient temperature and at an elevated temperature; and calculating said temperature coefficient of resistance based on said measured resistance values.
Preferably, at least one thermally-isolated micro-platform is provided and the functional resistor is placed on the at least one thermally-isolated micro-platform. According to an eighth broad aspect of the present invention, there is provided a circuit for calculating a temperature coefficient of resistance of a functional resistor, the circuit comprising: at least one thermally-isolated micro-platform on a substrate; a functional resistor on said at least one thermally-isolated micro-platform; heating circuitry for heating said functional resistor; measuring circuitry for measuring a resistance value of said functional resistance at ambient temperature and at an elevated temperature; and calculating circuitry for calculating said temperature coefficient of resistance based on said resistance value at ambient temperature and at an elevated temperature.
These and other features, aspects and advantages of the present invention will become better understood with regard to the following description and accompanying drawings wherein:. It should be noted that for the purpose of this disclosure, trimming is to be understood as increasing or decreasing the room-temperature resistance value of a resistor. It should also be noted that thermally-isolated is meant to describe an element that is isolated from other elements such that the heat flux proportional to temperature differential generated between the element and other elements, is generally low.
Electrically-isolated is meant to describe an element that is isolated from other elements such that the resistance between this element and other elements is very high e. The term signal is meant to describe any data or control signal, whether it be an electric current, a light pulse, or any equivalent. Furthermore, obtaining a constant or flat temperature distribution, T x , is equivalent to a relatively flat or substantially constant temperature distribution across a resistor.
The entire resistance cannot be at the same temperature since a portion of the resistor must be off the micro-platform. Therefore, obtaining a substantially constant temperature distribution across a resistor is understood to mean across a maximum possible fraction of the resistor.
A pulse is to be understood as a short duration of current flow. To underlie the invention herein, an outline and discussion of certain modes of heating and heat localization is in order.
Thermal and electro-thermal trimming of a resistor involves the application of heat to a target resistor for a certain time-period. Thus, almost by definition, all such purposeful trimming is done by a heat pulse or pulses. If the behavior of the resistor is well-known and highly predictable, effective trimming can be done with a single well-designed pulse.
It was described and named in by Leon Chua , completing a theoretical quartet of fundamental electrical components which comprises also the resistor , capacitor and inductor. Chua and Kang later generalized the concept to memristive systems. Several such memristor system technologies have been developed, notably ReRAM. The identification of genuine memristive properties in both theoretical and practical devices has attracted controversy. Chua in his paper identified a theoretical symmetry between the non-linear resistor voltage vs.
THE INDUSTRIAL WIKI
Year of fee payment : 4. Year of fee payment : 8. An integrated circuit package that comprises a lead frame, an integrated circuit located on the lead frame and a shunt resistor coupled to the lead frame and to the integrated circuit. The shunt resistor has a lower temperature coefficient of resistance than the lead frame, and the lead frame has a lower resistivity than the shunt resistor.
Basics of Ceramic Chip Capacitors
Now in its 22nd year, CMSE is the premier event focused on the design, reliability, and application of electronic components for use in avionics aerospace, military, and commercial space systems. At the conference, Vishay Dale will be displaying a wide range of military-qualified resistors with established reliability. These will include leaded through-hole metal film resistors; thick and thin film chip resistors; leaded and housed wirewound devices; and thick and thin film resistor networks. Featured products will include Vishay Huntington and Vishay Milwaukee ribwound and roundwire power resistors with power ratings to W and resistance values down to 0.
Direct-Write Technologies covers applications, materials, and the techniques in using direct-write technologies. This book provides an overview of the different direct write techniques currently available, as well as a comparison between the strengths and special attributes for each of the techniques. The techniques described open the door for building prototypes and testing materials. The book also provides an overview of the state-of-the-art technology involved in this field. Basic academic researchers and industrial development engineers who pattern thin film materials will want to have this text on their shelves as a resource for specific applications. Others in this or related fields will want the book to read the introductory material summarizing isuses common to all approaches, in order to compare and contrast different techniques. Everyday applications include electronic components and sensors, especially chemical and biosensors.
To browse Academia. Skip to main content. You're using an out-of-date version of Internet Explorer. Log In Sign Up. Evaluation of electrolessly deposited NiP integral resistors on flexible polyimide substrate Microelectronics Reliability, Markus Turunen. Tomi Laurila. Tuomas Waris. Evaluation of electrolessly deposited NiP integral resistors on flexible polyimide substrate. Microelectronics Reliability 45 — www. Turunen, Tomi Laurila, Jorma K.
US7249409B2 - Method for trimming resistors - Google Patents
Thick film technology is an example of one of the earliest forms of microelectronics-enabling technologies and it has its origins in the s. At that time it offered an alternative approach to printed circuit board technology and the ability to produce miniature, integrated, robust circuits. It has largely lived in the shadow of silicon technology since the s. Indeed, there is evidence that even early Palaeolithic cave paintings from circa BC may have been created using primitive stenciling techniques. With the advent of surface-mounted electronic devices in the s, thick film technology again became popular because it allowed the fabrication of circuits without through-hole components. This chapter will review the main stages of the thick film fabrication process and discuss some of the commonly used materials and substrates. It will highlight the way in which the technology can be used to manufacture hybrid microelectronic circuits.
Film resistor technologies have come a long way since metalised glass and cracked carbon films were first offered over eighty years ago as alternatives to the bulk material approaches of wirewound and composition. Metal oxide emerged in the s as a more stable film and was widely applied until ceding ground to metal film for precision and thick film for high power uses. Both of these technologies were then employed in the emerging SMD chip format. However, it would be a mistake to think that nothing is changing in the world of film resistors. This paper identifies three drivers of continued evolution and outlines some of the developments which are being made in response. The first driver is imperative to reduce environmental impact and is felt through legislated regulation and, indirectly, consumer pressure. Following this is continued expansion of the safe operating area, pushing back on the electrical rating limits which constrain miniaturisation of analogue circuits. And finally, rising demands for higher levels of stability and reliability in commercial and industrial applications are being met by the transition of technology developed for space and military applications. Two responses to the environmental driver are identified.
Microelectronics Packaging Handbook : Semiconductor Packaging. Rao Tummala , Eugene J.
Voltage Regulators It is often required that the output voltage from a power supply be maintained at a constant value regardless of input voltage or load variations. The device used to give us this control is the voltage regulator. Regardless of the specific operating device used, the action is basically the same: that of providing a constant value of output voltage from the power supply, despite any reasonable variations in input voltage or load current. A voltage regulator is an electronic device connected in the output of a power supply to maintain the output voltage at its constant rated value.
The purpose of this document is to provide an overview of the degradation process that can occur in metal oxide varistors MOVs. MOVs are variable resistors primarily consisting of zinc oxide ZnO with the function of limiting or diverting transient voltage surges. MOVs exhibit a relative high energy absorption capability which is important to the long term stability of the device. The growing demand of ZnO varistors is due to the nonlinear characteristics as well as the range of voltage and current over which they can be used.
The present invention relates generally to integrated circuit technology, and more particularly to temperature-compensated resistors and fabrication methods therefor. As the power output capability of MESFETs continues to improve, a single transistor can provide the power once provided by several transistors, thereby saving considerable costs and drastically reducing the size of the amplifier modules. The higher the power handling capability and efficiency that can be achieved, the greater will be the number of potential applications for MESFET amplifiers.