2010-12-25 13:32:55
views
Integrated circuits: There is a variety of packages which are used for integrated circuits. The package used depends upon the level of interconnectivity required. Many chips like the simple logic chips may only require 14 or 16 pins, whereas other like the VLSI processors and associated chips can require up to 200 or more. In view of the wide variation of requirements there is a number of different packages available.
For the smaller chips, packages such as the SOIC (Small Outline Integrated Circuit) may be used. These are effectively the SMT version of the familiar DIL (Dual In Line) packages used for the familiar 74 series logic chips. Additionally there are smaller versions including TSOP (Thin Small Outline Package) and SSOP (Shrink Small Outline Package).
The VLSI chips require a different approach. Typically a package known as a quad flat pack is used. This has a square footprint and has pins emanating on all four sides. Pins again are bent out of the package in what is termed a gull-wing formation so that they meet the board. The spacing of the pins is dependent upon the number of pins required. For some chips it may be as close as 20 thousandths of an inch. Great care is required when packaging these chips and handling them as the pins are very easily bent.
Other packages are also available. One known as a BGA (Ball Grid Array) is used in many applications. Instead of having the connections on the side of the package, they are underneath. The connection pads have balls of solder that melt during the soldering process, thereby making a good connection with the board and mechanically attaching it. As the whole of the underside of the package can be used, the pitch of the connections is wider and it is found to be much more reliable.
A smaller version of the BGA, known as the microBGA is also being used. As the name suggests it is a smaller version of the BGA.
2010-12-24 13:27:36
views
Transistors and diodes: These components are often contained in a small plastic package. The connections are made via leads which emanate from the package and are bent so that they touch the board. Three leads are always used for these packages. In this way it is easy to identify which way round the device must go.
2010-12-23 19:15:41
views
Passive SMDs: There is quite a variety of different packages used for passive SMDs. However the majority of passive SMDs are either resistors or capacitors for which the package sizes are reasonably standardized. Other components including coils, crystals and others tend to have more individual requirements and hence their own packages.
Resistor and capacitor packages have a variety of packages. These have designations that include: 1812, 1206, 0805, 0603, 0402, and 0201. The figures refer to the dimensions in hundreds of an inch. In other words the 1206 measures 12 hundreds by 6 hundreds of an inch. The larger sizes such as 1812 and 1206 were some of the first that were used. They are not in widespread use now as much smaller components are generally required. However they may find use in applications where larger powers are needed or where other considerations require the larger size.
The connections to the printed circuit board are made through metallised areas at either end of the package.http://www.jbcapacitors.com/
2010-12-22 19:7:7
views
SMDs, i.e. SMT components, by their nature are very different to the traditional leaded components. They can be split into a number of categories:
- Passive SMDs
- Transistors
- Integrated circuits
2010-12-17 2:29:32
views
Capacitors naturally wear out after extended periods of use. Most capacitors are designed to operate for several thousand hours. Here is the projected lifespan for a typical capacitor, rated for 4,000 hours of operation at an average core temperature of 167 degrees Fahrenheit (75℃).
| Core temperature in degrees F (and ℃) | Projected lifespan in hours of operation |
| 221(105) | 500 |
| 203(95) | 1,000 |
| 185(85) | 2,000 |
| 167(75) | 4,000 |
| 149(65) | 8,000 |
| 131(55) | 16,000 |
| 113(45) | 32,000 |
2010-12-16 15:7:24
views
Capacitors on a motherboard are used to absorb spikes in electrical current and to smooth the flow of power on the motherboard, protecting all of the computer’s components.
Contact our jb, as we are manufacturer of these capacitors and you also contact us if you have technical questions regarding these parts. jb (www.jbcapacitors.com) is a good place to find good capacitors. Our salesman is available to your e-mailed at info@jbcapacitors.com.
2010-12-13 14:38:15
views
Voltage to Current Convertor
When driving the input (base) of a transistor gain stage:
you must convert the input voltage to a current by using a voltage to current convertor --a resistor.
Current to Voltage Convertor
When deriving a voltage from the collector of a transistor amplifier stage:
you convert the output (collector) current into a voltage by using a Current to Voltage convertor in the collector circuit--you guessed it--a resistor.
2010-12-10 12:31:0
views
Polarized fixed capacitor 
A polarized ("polar") capacitor is a type of capacitor that have implicit polarity -- it can only be connected one way in a circuit. The positive lead is shown on the schematic (and often on the capacitor) with a little "+" symbol. The negative lead is generally not shown on the schematic, but may be marked on the capacitor with a bar or "-" symbol. Polarized capacitors are generally electrolytics.
Note that you really need to pay attention to correctly hooking a polarized capacitor up (both with respect to polarity, as well as not pushing a capacitor past its rated voltage). If you "push" a polarized capacitor hard enough, it is possible to begin "electrolyzing" the moist electrolyte. Modern electrolytic capacitors usually have a pressure relief vent to prevent catastrophic failure of the aluminum can (but don't bet your eyesight on this).
2010-12-7 1:5:59
views
A capacitor is an electronic device for storing charge. Capacitors can be found in almost any complex electronic device. They are second only to resistors in their There are many different types of capacitor but they all work in essentially the same way. A simplified view of a capacitor is a pair of metal plates separated by a gap in which there is an insulating material known as the dielectric. This simplified capacitor is also chosen as the electronic circuit symbol for a capacitor is a pair of parallel plates as shown 
.
jb Various types of capacitor
2010-12-6 4:20:12
views
Symbol:T
Unit:(s)
When a capacitor discharges its charge throught a resistor, the charge of the capacitor decreases with time. The decreasing charge follows an exponential decay curve.
http://www.jbcapacitors.com/
