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Kapton Copper
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 KAPTON COPPER CLAD .003"x12"x24" 2 SIDES 5574-2  US $33.00
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 32 AWG 7/40 KAPTON, TEFLON, COATED COPPER, 2C AEROSPACE FLAT HOOKUP WIRE, 50' +/ US $24.95
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Silicone rubber keypads are the most widely used form of switching technology today. They offer reliability, long life and design flexibility. There are some simple rules and basic design elements to consider when designing a silicone rubber keypad.
Key design will vary with the functional and aesthetic requirements of the application. It is possible to mold a key in almost any shape and to fit almost any configuration. It is important to remember that the key shape will affect the feel of the key. While a circular shaped standard key will have a consistent feel across the entire surface a half moon shaped key will respond different depending upon where the key is pressed.
Once you have decided upon a key shape and layout; the next item to consider is the method for marking the rubber and creating legends. There are three common methods for marking keypads; printing, laser etching, and plastic key caps.
Printing
Printing is the most common method of marking rubber. The rubber is fixtured to flatten the key top then screen printed. There is no limit to the number of colors available. The arc of the key top determines how far printing must be set back from the edge of the key.
There are currently several options available for improving legend life with printed rubber.
o Plastic Key Caps - custom molded clear plastic is adhered over the legend or molded into the rubber
o Oil or Epoxy Coating - coating is deposited on the top surface of the key over printing, available in matte, semi-gloss, or gloss finish
o Drip Coating - drip coating can be hard or flexible. It adds a glossy layer over the key top. It can not be used on some keys with sharp angles. Hard coatings are subject to cracking if the key has large surface areas.
o Parylene Coating - offers the highest level of protection for a non-plastic coating. Parylene bonds to the rubber at the molecular level.
Laser Etching
Laser etching is especially well suited for applications where the keypad is backlit. Etching typically involves three production steps.
1) Translucent rubber (any color) is sprayed with a translucent base coat ink which will be the legend color that is visible to the user.
2) Rubber is sprayed with an opaque top coat ink which will be the overall color of the keypad.
3) The top coat of ink is laser etched away using high speed etchers to reveal the base coat.
Alternatively, you can decide to use a single translucent or opaque rubber ink and laser etch the legends revealing the color of the rubber that is used.
Plastic Key Caps
The longest lasting legend type is custom molded plastic. Plastic legends will not wear out. Many cell phone keypads are designed with plastic keys over rubber.
Functional Design Considerations
Snap Ratio & Tactile Feel
The snap ratio of a keypad determines the tactile feel experienced by the user. The recommended snap ratio for designers to maintain is 40%-60%; if dropped below 40% the keys will lose tactile feel but have an increased life. Loss of tactile feel means the user will not receive a 'click' feedback during actuation.
Snap ratio is calculated by taking the [ACTUATION FORCE (F1) - CONTACT FORCE (F2)] / ACTUATION FORCE (F1).
Most customers do not design the web and rely upon the manufacturer to design and meet the requirements.
Reducing Rocking Action
A common problem with rubber keypad design is the rocking action that can occur when a key is pushed. Rocking action can reduce the life of the keypad, make actuation difficult for the user, and cause other problems. The following suggestions will assist in reducing this problem.
o Add stabilizing posts on base of key
o Keep key stroke as near 0.8mm as possible
o Keep web length to a minimum
o Keep web angle close to 40°
o Actuation force of 80-150 grams for keys 10-15 mm high and 150-175 grams for keys 15-25mm high
Return force should also be set at 30-35 grams to ensure that keys do not stick.
Switch Life
The web design and the durometer of the rubber are the two factors that affect keypad longevity most. The design should reduce stress on the rubber if long life is desired. Using higher durometer silicone, increasing the actuation force, or increasing the stroke will all decrease the keypads life.
Rubber Hardness
Rubber hardness for a keypad can vary between 30 and 70 durometer (Shore A). Typically, most keypads are built between 40 and 60 durometer.
Minimum Key Height
For any design, calculate the minimum key height as follows; Keypad Base Thickness + Bezel Thickness + Stroke of Key + 0.5mm.
Contacts
The carbon pill is the most common contact because of its long life (>10 million actuations) and low resistance (Printed Circuit Board Design
The rubber contacts need to make contact with a circuit underneath. Rubber key mats themselves are very reliable in operation. However, when considering a PCB design, the environment in which the keypads are used must be considered to ensure that the complete switching unit is reliable. imum of 1.25 times.
Flexible Printed Circuit Design
Rubber keypads are typically used with printed circuit boards. However, many rubber keypads are also used with flexible printed circuits. Flexible circuits can be made of polyester or copper (Kapton).
A graphic of a silicone keypad with descriptions of the items above is available at [http://www.rspinc.com/silicone-keypad-8.php]
Mike Ryan is the owner and President of RSP, Inc in Milwaukee, WI & Shenzhen, China. He has over 10 years experience designing, building, and testing membrane switches, touch screens, silicone rubber keypads, plastic injection molding and other user interfaces. Visit http://www.rspinc.com for more information. RSP, Inc. is a global supply partner for medical industry, consumer products, and manufacturing. If you need help with your design call 414-546-4417 to talk to a design expert.
Power electronic substrate
Direct bonded copper substrate
Structure of a direct bonded copper substrate (top) and an insulated metal substrate (bottom).
Direct bonded copper (DBC) substrates are commonly used in power modules, because of their very good thermal conductivity. They are composed of a ceramic tile (commonly alumina) with a sheet of copper bonded to one or both sides by a high-temperature oxidation process (the copper and substrate are heated to a carefully controlled temperature in an atmosphere of nitrogen containing about 30 ppm of oxygen; under these conditions, a copper-oxygen eutectic forms which bonds successfully both to copper and the oxides used as substrates). The top copper layer can be preformed prior to firing or chemically etched using printed circuit board technology to form an electrical circuit, while the bottom copper layer is usually kept plain. The substrate is attached to a heat spreader by soldering the bottom copper layer to it.
Ceramic material used in DBC include:
alumina (Al2O3), which is widely used because of its low cost. It is however not a really good thermal conductor (24-28 W/mK) and is brittle.
aluminium nitride (AlN), which is more expensive, but has far better thermal performance (> 150 W/mK).
beryllium oxide (BeO), which has good thermal performance, but is often avoided because of its toxicity when the powder is ingested or inhaled.
One of the main advantages of the DBC substrates is their low coefficient of thermal expansion, which is close to that of silicon (compared to pure copper). This ensures good thermal cycling performances (up to 50,000 cycles). The DBC substrates also have excellent electrical insulation and good heat spreading characteristics.
A related technique uses a seed layer, photoimaging, and then additional copper plating to allow for fine lines (as small as 50 microns) and through-vias to connect front and back sides. This can be combined with polymer-based circuits to create high density substrates that eliminate the need for direct connection of power devices to heat sinks.
Insulated metal substrate
Insulated metal substrate (IMS) consists of a metal baseplate (aluminium is commonly used because of its low cost and density) covered by a thin layer of dielectric (usually an epoxy-based layer) and a layer of copper (35 m to more than 200 m thick). The FR-4-based dielectric is usually thin (about 100 m) because it has poor thermal conductivity compared to the ceramics used in DBC substrates.
Due to its structure, the IMS is a single-sided substrate, i.e it can only accommodate components on the copper side. In most applications, the baseplate is attached to a heatsink to provide cooling, usually using thermal grease and screws. Some IMS substrates are available with a copper baseplate for better thermal performances.
Compared to a classical printed circuit board, the IMS provides a better heat dissipation. It is one of the simplest way to provide efficient cooling to surface mount components.
Other substrates
When the power devices are attached to a proper heatsink, there is no need for a thermally efficient substrate. Classical printed circuit board (PCB) material can be used (this method is typically used with through-hole technology components). This is also true for low-power applications (from some milliwatts to some watts), as the PCB can be thermally enhanced by using thermal vias or wide tracks to improve convection. An advantage of this method is that multilayer PCB allows design of complex circuits, whereas DBC and IMS are mostly single-sided technologies.
Flexible substrates can be used for low-power applications. As they are built using Kapton as a dielectric, they can withstand high temperatures and high voltages. Their intrinsic flexibility makes them resistant to thermal cycling damage.
Ceramic substrates (thick film technology) can also be used in some applications (such as automotive) where reliability is more important than good power dissipation.
References
^ Source: Liu, Xingsheng (February 2001). "Processing and Reliability Assessment of Solder Joint Interconnection for Power Chips". Virginia Tech Dissertation
^ Source: Curamik, manufacturer of DBC
^ Source: Liu, Xingsheng (February 2001). "Processing and Reliability Assessment of Solder Joint Interconnection for Power Chips". Virginia Tech Dissertation
^ Source: Hytel Group, manufacturer of copper on ceramic substrates
^ Source: The Bergquist company
^ Source: AI Technology, Inc.
^ Thermal Management in High-Density Power Converters , Martin Mrz, International Conference on Industrial Technology ICIT'03 Maribor, Slovenia, December 10 - 12, 2003 (pdf document, last accessed 6/5/06)
^ Quick presentation of several applications and features of the thick film substrates
The thermal performances of IMS, DBC and thick film substrate are evaluated in Thermal analysis of high-power modules Van Godbold, C., Sankaran, V.A. and Hudgins, J.L., IEEE Transactions on Power Electronics, Vol. 12, N 1, Jan 1997, pages 3-11, ISSN 0885-8993 (restricted access)
Categories: Power electronicsHidden categories: Orphaned articles from February 2009 | All orphaned articles
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Orion Cobalts? Rating please?
Ok, Im looking to upgrade my system agian since i got a new amp... Im running a 980 watt power acoustik amp. Im looking at buying two 'Cobalt 12" subs' off of ebay... The thing is i havent heard of them. Heres the info on them. They are made by orion, which i HAVE heard of, and my friend has a pair and they SLAM.
500W PEAK POWER
SINGLE VOICE COIL
SENSITIVITY: 87.2 DB @ 1W/1 M
REVERSIBLE TOP GASKET
LARGE COPPER-WOUND KAPTON VOICE COIL
AUTO TENSION PUSH TERMINALS
FLAT CONEX SPIDER WITH LOOP STITCHES TINSEL LEADS
DIM: 5.51"D X 12.4"W
Are they decent? AND if not what would you recommend? Ive looked for some kickers, but i havent found many that Im fond of.. And MTX's are not pushing what i want
id would go with 2 type r 12' alpine subs and a ps2-2600 amp thats what im running and it goes offfffffffffffffff!!!!!!!!!!!!!!
DuPont Introduces New Kapton Films For Flexible And Thin Film Photovoltaic Applications
DuPont Circuit & Packaging Materials announces the commercial availability of DuPont Kapton polyimide films engineered for thin film and flexible photovoltaic substrates.
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