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KEEP Kentucky Electronics Education Project Dr. Janet Lumpp - Electrical and Computer Engineering Dr. Kelly Bradley - Educational Policy Studies and Evaluation University of Kentucky July 2005 KEEP Objectives Educate teachers regarding Electronic assembly technologies Properties of electronic materials Develop curriculum materials Solicit industry partnerships Organize hands-on projects and fieldtrips Encourage young students to consider technical and engineering careers July 2005 KEEP Workshop KEEP Background Classroom activities Teacher workshops Independent implementations West Jessamine High School The Lexington School Lafayette High School Girls in Science - students and teachers KSTA PD Session - November 2005 July 2005 KEEP Workshop KET Partnership CD-ROM Coming Soon Studio session Filmed “cooking show” circuit steps - Dec’04 Editing now SMC, Inc. - Electronic assembly process Filmed manufacturing equipment - June’05 Editing now NAVSEA Crane - PCB fabrication Filming to be scheduled after renovation July 2005 KEEP Workshop Electricity to Electronics Electricity and Magnetism Principles and definitions Circuit elements, symbols and diagrams Electronic Circuits Add semiconductor devices Physical size of components 2D and 3D locations and connections July 2005 KEEP Workshop Types of Components Through hole or Surface Mount Passive or Active July 2005 KEEP Workshop Printed Circuit Boards PCB = Printed Circuit Board Copper conductor Epoxy/Glass insulator Green coating = solder mask Single or double sided copper Single or multiple layers Through holes = vias Component leads Connect layers Plated with copper July 2005 KEEP Workshop How to Solder Soldering iron = heat source Heat copper ring and component lead Bring in solder wire Activate flux to clean oxides off of metal surfaces Solder alloy melts and wets clean metal surfaces Pull solder wire away from joint Remove soldering iron Coat soldering iron tip with solder to prevent oxidation between uses July 2005 KEEP Workshop Project Steps Layout pattern drawn from schematic Print layout on Press-N-Peel paper Iron pattern on to clean copper PCB Soak off paper backing, repair lines Etch excess copper in sodium persulfate Remove remaining toner (etch resist) Drill through holes Insert components Hand solder July 2005 KEEP Workshop Implementation Options Purchase or borrow tools Purchase circuit project kits Solder only Drill and Solder Full process On-going PD Workshops Science, math, technology teachers Core team in one school or district Develop instructional units July 2005 KEEP Workshop Science Standards and KEEP SC-M-1.3.2 Heat energy moves in predictable ways, flowing from warmer objects to cooler ones, until both objects reach the same temperature. Soldering iron converts electrical energy to heat energy. Must make contact with cooler objects to transfer heat by conduction. The temperature of the iron is greater than the melting point of the solder. Solid-liquid-solid transformation at each solder joint. July 2005 KEEP Workshop Science Standards and KEEP SC-M-1.3.1 Energy is a property of many substances and is associated with heat, light, electricity, and sound. Energy is transferred in many ways. SC-M-1.3.5 Electrical circuits provide a means of transferring electrical energy when heat, light, sound, and chemical changes are produced. Flashing LED Circuit - heat, light, electricity, chemical to electrical (battery) energy conversion Buzzer Circuit - heat, light, electricity, sound, chemical to electrical (battery) energy conversion July 2005 KEEP Workshop Science Standards and KEEP SC-H-1.1.1 Matter is made of minute particles called atoms, and atoms are composed of even smaller components. … The electric force between the nucleus and the electrons holds the atom together. SC-H-1.2.1 Atoms interact with each other by transferring or sharing outermost electrons. These outer electrons govern the chemical properties of the element. Electrons and chemical bonding determine which materials are conductors, insulators and semiconductors. All types of materials are needed in microelectronics. Different materials must bond without contamination. July 2005 KEEP Workshop Science Standards and KEEP SC-H-1.3.1 Chemical reactions occur all around us and in every cell in our bodies. These reactions may release or consume energy. Rates of chemical reactions vary. Reaction rates depend on concentration, temperature, and properties of reactants. Catalysts speed up chemical reactions. Etching Copper - solution of sodium persulfate in water Solution is heated to increase the reaction rate. As copper is etched, the reaction rate slows (concentration). Catalyst can be added to increase the reaction rate again. July 2005 KEEP Workshop Math Standards and KEEP MA-E-1.1.5 Multiple representations of numbers (e.g., drawings, manipulative, symbols) MA-M-1.1.6 Representation of numbers and operations in a variety of equivalent forms using models, diagrams, and symbols (e.g., number lines, 10 by 10 grids, rectangular arrays, number sentences) Resistor color code - colors represent numbers 0 to 9 Two digits and order of magnitude, 123 = 12 X 103 Tolerance of 5% (gold) or 10% (silver) July 2005 KEEP Workshop Resistor Color Code http://www.mechatronics.me.vt.edu/VT84Construction/resistorcodes.html July 2005 KEEP Workshop Science Standards and KEEP SC-H-3.5.5 Human beings live within the world’s ecosystems. Human activities can deliberately or inadvertently alter the dynamics in ecosystems. These activities can threaten current and future global stability and, if not addressed, ecosystems can be irreversibly affected. Science in Personal and Social Perspectives -describe the individual’s roles and responsibilities in the following areas: changes in populations, resources and environments including ecological crises and environmental issues, natural hazards, science and technology in society, and personal and societal issues about risks and benefits. Electronics manufacturing uses tremendous amounts of metals, acids, water, energy, etc. What are the safety issues for workers? What are the environmental issues? What are the economics of improving the manufacturing methods? July 2005 KEEP Workshop Math, Science and KEEP Science as Inquiry Science and Technology Science in Personal and Social Perspective MA-E-1.1.4 Place value, expanded form, number magnitude (order, compare) to 100,000,000, and decimals through thousandths. Orders of magnitude in dimensions, memory, pixels, processor speed. Why is it that a new PC with 24 GB of RAM is not any bigger than an old PC with 24 MB of RAM, a 1000 times increase in memory? Why is it that a 10 MB hard drive used to be the size of a shoe box and now 40 GB fit in an iPod in your hand running on batteries? Why does the microprocessor in a new laptop PC run 5 times faster than an old laptop, but the batteries last longer in the new laptop? July 2005 KEEP Workshop Math Standards and KEEP MA-H-2.1.1 Students will describe properties of and give examples of geometric transformations and apply geometric transformations (translations, rotations, reflections, dilations), with and without a coordinate plane, to both real-world and mathematical situations. MA-H-2.2.1 Students will perform transformations (reflections, translations, rotations, dilations) on figures. MA-H-2.2.2 Students will classify two-dimensional and three-dimensional geometric figures according to their characteristics such as lengths of sides; angle measures; and number of sides, faces, edges, and vertices. Students will describe the intersection of a plane with a three-dimensional geometric figure. Identify components by describing the three dimensional shapes of the packages and leads. Recognize components by their two dimensional projections as seen by visual alignment systems. Sophisticated vision systems see color and read labeling. XY Locations on a circuit board - placing components, dispensing dots of adhesive, wirebond pads around a chip July 2005 KEEP Workshop Math Standards and KEEP MA-H-2.3.4 Students will understand how a change in one or more dimensions of a geometric shape affects perimeter, area, volume, or surface area. Area density = percentage of board area occupied by components. Circuits are miniaturized by choosing smaller components and reducing the spacing between objects. Use layout software to compare alternative designs and calculate area density. July 2005 KEEP Workshop Math Standards and KEEP MA-H-4.1.1 Students will understand the concept of a function and roles of independent and dependent variables. MA-H-4.1.4 Students will identify linear, quadratic, absolute value, and exponential functions from graphs and equations. MA-H-4.1.5 Students will apply direct and inverse variation to both realworld and mathematical problems. MA-H-4.3.2 Students will understand how formulas, tables, graphs, and equations of functions relate to each other. I-V (Current-Voltage) relationships for resistors, capacitors, inductors Series and parallel combinations of resistors, capacitors, inductors Current and voltage divider expressions for resistors 555 timer formulas July 2005 KEEP Workshop I-V Relationships Resistors Ohm’s Law V=IR Capacitors ic(t) = dvc(t)/dt Inductors vL(t) = diL(t)/dt July 2005 KEEP Workshop Kirchoff’s Laws Kirchoff’s Voltage Law - KVL The sum of all voltages around a closed loop is zero. S Vn = 0 Kirchoff’s Current Law - KCL The sum of all currents entering a node is zero. S In = 0 July 2005 KEEP Workshop Series and Parallel Elements in series have the same current flowing through them. Elements in parallel have the same voltage across them. Series R, Series L, Parallel C Rs = S Rn Parallel R, Parallel L, Series C 1/RP = S 1/Rn Two R in parallel RP = (R1R2)/(R1 + R2) July 2005 KEEP Workshop Current and Voltage Dividers Combine Ohm’s Law and Kirchoff’s Laws to develop short cut formulas Voltage divider v1 = v(R1/(R1+R2)) Current divider i1 = i(R2/(R1+R2)) July 2005 KEEP Workshop Capacitor Discharging and Charging DC (battery) sources Capacitor is initially charged to a voltage V0 Discharging v(t) = V0e-t/t t = RC = time constant Charging from V0 to Vs, Vs = steady state v(t) = Vs +(V0-Vs) e-t/t If V0 = 0, v(t) = Vs(1 - e-t/t) July 2005 KEEP Workshop