Sunday 12 August 2012


Industrial Engineering Research Paper Summary Project


                                                            

Presented by
Ruby Shah
Roll no. 119
PGDIE 42

Research on the Lean Six Sigma Supplier Recovery Management


INTRODUCTION

The supplier recovery management is a topic of tremendous importance of supplier management. In the operation decisions of a firm, the supplier recovery management has a great influence on the supply chain design
in terms of transportation and distribution planning and production planning. Reliable supplier recovery management may be done to minimize the damages of the manufacturer and the supplier. Lean six sigma is an advanced managing method and is utilized by more and more enterprises. Based on lean six sigma, the supplier recovery management can identifY better performing suppliers in a supply chain and creat more benefit for suppliers and manufacturers. The supplier recovery management has been considered as a complex problem in the literature due to the several following reasons:

( 1) Individual suppliers may have different performance
characteristics for different criteria;

(2) There may be time constraints on the delivery of items.
Within these time constraints, some criteria for the supplying
the items may become important, while other criteria may not
be the dominant ones;

( 3 ) Constraints related to suppliers' quota allocation,
number of suppliers to employ, minimum and maximum order
quantities, use of minority suppliers etc.

LEAN SIX SIGMA SUPPLER RECOVERY MANAGEMENT

Face on the commercial competition, enterprises must focus on the velocity, cost and benefit simultaneously. The lean six sigma combined Lean Production and Six Sigma into a new powerful managing measure. Its essence is to
eliminate any waste and to diminish defects. The company usually uses Lean production into the producing process to solve manufacturing problems, and used Six Sigma into the upper or overall management or some important projects managing. The core of Lean Six Sigma is the "JIT producing", "zero stocks", "3.4 defects percent million". The supplier recovery is defined that recovery, from a supplier, for any costs incurred by an enterprise resulting from a supplier's failure to perform to contractual requirements, in
terms of delivery, quality, performance, or other contractual element. In the supplier recovery management, early notification is the most pivotal element. Early notification can come ture faster communication and resolution of supplier caused field defects. As usual, the recovery opportunity
sources are as follows: 
(1) internal defect - defect found in the enterprise; 
(2) external defect - defect found in the field; 
(3) premium transportation supplier caused premium transportation costs; 
(4) Luidated damages: costomer incurredluidated damages which is supplier caused; 
supplier liquidated damages in contract with an enterprise. With the theory of Lean Six Sigma and the tools of DMAIC to analyze and improve the supplier recovery process, the befmit between suppliers and enterprises can be
maximized. Due to Lean Six Sigma's perfections and advancement, the Lean Six Sigma supplier recovery management becomes one of the most effective
management.


ONE EXAMPLE OF THE SUPPLIER RECOVERY MANAGEMENT

This example is about the supplier recovery management and the data are collected from a firm. The enterprise uses the early notifition process to resolve the failture of suppliers.

A. Early notification process

In each step one day or one to three days will be spent to resolve the defect.each step will spend one day or some days. In the third step , QE (quality engineer) will do the three jobs: technolygy assessment; request part return; request RCA. During the four steps the last step is the most important stage. In this procedure the supplier is the key element. Supplier mustfirstly review the case which would spend one day or so. Secondly suppliers will take one or two days to ask for missing information to field or QE. Supplier is expected to respond within two business days (day of receipt + 2) to make
the response. Responses must conform to one of the 5 options
(1) fix at site or technology guidance
(2) accept responsibility and authorize the firm to fix
(3)send a replacement part
(4)repair or refurbish the part at supplier site
(5) refute responsibility.
 Supplier must provide a part return logistics charge code or carrier name if part return is requested for RCA.For support the upper steps suppliers must update engineer metrics, update clarify with supplier decision ans QE
comments, update clarify with revised supplier decisions where applicable.
For QE, they should support engineer team to identify correct supplier name on SN request cases. If supplier "refutes responsibility", QE must advise if this is a supplier caused defect or not. QE must support any supplier requests for more
information and insure their response is received by three days.The other else bounden duties invole: update clarify with QE comments (timming is critical when "refute" is valid - complete by three days), and review and proactively act ondaily engineer metrics. All proactive effort can reduce defect impact. In the firm the status is over 300 suppliers are enabled, less to 1000 cases processed to YTD, the program expansion is ongoing. The benefits is spent on the timely customer issue resolution, early supplier engagement, reduced cost impact, driving timely communication and RCA.The firm applied the early notification in 2009, and achieved great success (explained as fig.3). 2009-YTD EN metrics are as follows: 1,215 defects and recoveried $13.8($MM), processed 1,059 defects and recoveried $8.0($MM); 8 of 10 new suppliers added, 2 pending; the defming system modification, 20 suppliers ID'd to train.


B. Supplier recovery process

The supplier recovery CTQs are: accountability, timeliness of recovery, recovery rate. The Goal is to maximize recovery rate by establishing a time sensitive (digitized) workflow based on a robust data capturing system with cefmed handoffs and ownership.In this step, the soucing roles and responsibilities is very important. The quality engineer determines the problem of quality if supplier is at fault; The sourcing commerical person informs supplier of recovery of recovery to be back billed or negotiateds recovery amount; The business recovery leader(BRL) makes recovery reporting and recovery process improvements.The provess makes 36%reduction in total backlog - $35.8MM (EOY 06) to $22.9MM.

C. the opportunity of supplier recovery: Sourcing COF

The most effective and advantaged opportunity of supplier recovery is sourcing COF. Only control the sorucing COF, decrease the occupation of cost, the suppler recovery will realize smoothly favorably. 






CONCLUSION
The supplier management is the key problem of supply chain management, so enterprises couldn't ignore the problem of the supplier recovery management. To apply the Lean Six Sigma into Supplier Recovery will develop a new
method and way to manage the suppliers recovery.Enterprises can require more and more economical results.The case quoted and discussed just proved the early notification process is very powerful and the recovery
process is very effectively and practicefully.The core thinking of Lean Six Sigma - saving and making the defects minimum is also the core of Lean Six Sigma supplier recovery management. This kind of study and demonstration is very significant and useful.

Saturday 11 August 2012



IE ASSIGNMENT

                 Engineering Research Paper Summary Project                                                                     


                                                   
PRESENTED BY
RUBY SHAH
ROLL.NO.119
PGDIE42

RFID Based Attendance System



                                   INTRODUCTION

Traditionally the attendance at an establishment is usually done in abook register. It is time consuming. It is very difficult to verify theattendance over long periods. This method is very time consuming andvery difficult to verify the attendance over a week or above. Keepingattendance registers is space consuming. Here chances of doingmalpractice in marking attendance are high.RFID based attendance system uses RFID tags for each person. Aperson marks the attendance by swiping the tag near RFID reader module.The attendance is temporarily saved in the EEPROM. At any time thecircuit can be connected to a computer and the attendance is moved fromEEPROM to a text file in computer. It has following advantages. (1)Simplicity and reliability, (2) Saving attendance in a computer allows easyverification and longer record keeping.It works on radio frequency transmitters and receivers. Each personis given a RF ID card which is having a unique code. When it is swiped ona RF ID card reader, it reads the code and is stored. The attendance istemporarily saved in the EEPROM. At any time the circuit can beconnected to a computer and the attendance is moved from EEPROM to atext file in computer. The advantage of this system is simplicity andreliability. Saving attendance in a computer allows easy verification andlonger record keeping.

Block Diagram






EXPLANATION : RFID READER 
The DT125R series RFID Proximity OEM Reader Module has a built-in antenna in minimized form factor. It is designed to work on the industrystandard carrier frequency of 125 kHz. This LF reader module with aninternal or an external antenna facilitates
communication with Read-Only ransponders type UNIQUE or TK5530 via the air interface. The tag datais sent to the host systems via the wired communication interface with aprotocol selected from the module pinout. The LF DT125R module is bestsuited for applications in Access Control, Time and Attendance, AssetManagement,Handheld Readers, Immobilizers, and other RFID enabledapplications.The AUTOMATIC DATA COLLECTION Technology usedin th RFID reader.
Features
•Selectable UART or Wigand26.
•Plug-and-Play, needs +5V to become a reader.
•No repeat reads.
•LED/Beeper indicates tag reading operation.
•Excellent read performance without an external circuit.
•Compact size and cost-effective very efficient module for portable readers.

                               
 Data Transmission is in ASCII Standard. Data read from the tag isManchester encoded. The Manchester encoded data is decoded to ASCIIstandard. Decoded data is sent to the UART serial interface for wiredcommunication with the host systems. ASCII data format is shown below:

Power supply

Almost all electronic devices used in electronic circuits need a dcsource of power supply to operate .The source of dc power is used toestablish the dc operating points for the passive and active electronicdevices incorporated in the system. The combination of a transformer, arectifier, and a filter constitutes an ordinary dc supply, also called anunregulated power supply. For many applications in electronicsunregulated power supply is not good because of the following reasons.
•Poor regulation.
•Variations in the ac supply main.
•Variations in temperature.
                                CIRCUIT DIAGRAM

WORKING
Microcontroller reads time from real time chip DS12887. Whenever a RFID tagis brought near RFID module, it sends the card number in ASCII fomat to themicrocontroller. The microcontroller compares this number with those numbers in theEEPROM. If match is found, it first check whether it is a master card, then it displaysmenu for master card. If not, it displays the ID number and then sends the time and datedetails along with ID number to EEPROM for marking daily attendance. If no matchesfound, the microcontroller displays ‘Card Not Programmed’ in LCD.Master card menu consists of set time, add, edit, delete, transfer. The variousoptions are selected using the keypad keys- up, down, enter, cancel. Keypad encoder converts the key pressed into corresponding hex file. The output from RFID is given asthe serial input. The card ID number is 8 bytes long and two extra bytes serve as startand stop bits.Set time: It is used to edit the time of RTC. The time is entered using the keypad.Add: It is used to add a new tag and store the new tag number and ID number toEEPROM.Edit: It is used to edit the card ID number. The new ID number is entered throughkeypad.Delete: It is used to delete a card from record.Transfer: This option is used to transfer the marked attendance stored in EEPROM tothe computer.MAX232 is used to convert the TTL voltage to RS232 compatible voltage. Realtime clock is used to provide the date, month, and year details for marking theattendance


PROGRAM FLOW CHART

                                   FABRICATION OF PCB
Making a Printed Circuit Board is the first step towards building electronicequipment by any electronic industry. We should keep in mind that qualityof soldering affects the quality of the output. The procedure for fabricatingthe PCB for setting up the circuit of any multipurpose project is describedbelow.PCB Making:The making of PCB is as much as art on a technique particularly so whenthey are to fabricated in very small numbers. There are several ways of drawing PCB patterns and making the final boards.The making of PCB essentially involves two steps:1. Preparing PCB drawing2. Fabricating PCB from the drawingThe traditional method of drawing with complete placement of parts,taking a photographic negative of the drawing, developing the image of thenegative formed on photo sensitized copper plate and dissolving the excesscopper by etching is a standard practice being followed by large scaleoperations. However for small-scale operations, where large numbers of copies are not required, the cost saving method presented here may beadopted.PCB Drawing:Making of PCB drawing involves placement of components, locatingholes, optimum area each component should occupy shape and size of padsfor the components, track size and spacing and prevention of overcrowdingof components at a particular area. With these details the sketch of thePCB is made. For anchoring leads of component 1mm diameter holes andfor fixing PCB holding screws to the 3mm holes diameter can be made.Following these hints, a sketch of PCB is made.
 The fabrication of the PCB starts by transferring the PCB drawing onto acopper clad sheet. For a small number of PCB, a direct photographictransfer of the PCB drawing from a negative image of the drawing to aphoto sensitized copper clad sheet is carried out. The copper from theunexposed area is later etched away. For large quantity production, screenprinting method is used to transfer the PCB drawing image to the copper clad sheet. For etching the copper clad sheet 20-30grms of ferric chloride75ml of water heated to about 60degree Celsius may be used . The copper clad sheet is placed in the solution with its copper side upwards in a plastictray. Stirring the solution helps in speedy etching. The dissolution of unwanted copper would take about 45min. If etching takes longer, thesolution may be heated again and the process is repeated. The paint on thepattern can be removed by rubbing with a rag soaked in thinner, turpentineor acetone. The PCB can then be washed and dried.The pads are drilled with proper drill sizes of 0.9mm, 1mm, 3mm etc for the leads and mounting holes.




                                MERITS AND DEMERITS
Advantages
Unauthorized attendance can be avoided.
Easy to verify the attendances over a long period of time.
Promiscuity of tags.
•Non-contact and non-line-of-sight.
•Space consumption can be reduced to a greater extent.
No need to connect this system to a P.C always.
Disadvantages
Identity theft.
System affected by metal interference.
Very little power available to digital portion of the IC, limited functionality.
•Lack of standards and protocols




Wednesday 8 August 2012

              INDUSTRIAL ENGINEERING
            ASSIGNMENT ON PRODUCT MANUFACTURING
 



        Presented by 
         Ruby Shah (PGDIE 42) 119
           Srajan Shrivastava (PGDIE 42) 97


Manufacturing of 
Junction Transistor



INTRODUCTION
Since the first point-contact bipolar transistor, invented in 1947, there has been much progress in the development of very high density integrated circuits (IC), often referred to as very large scale integration (VLSI).Although many new devices have been invented, the bipolar transistor is still one of the key devices in every IC. Bipolar devices offer the following advantages compared to CMOS: high current drive ability, high frequency response, good matching, analog applications, low noise and high trans-conductance. Diffusion and ion implantation are the two key processes to introduce a controlled amount of dopants into semiconductors and to alter the conductivity type. In the fabrication of semiconductor devices, the diffusion process must give repeatable, controlled value of impurity concentration and depth of diffusion. This requires accurate control temperature, the impurity surrounding the slice and duration of the process. Typically the diffusion process can be divided into two stages called pre-deposition or deposition and drive-in.
Manufacture of Junction Transistors
As most of the transistors used at present in radio receivers are made by the alloy-junction method, only this technique will be described. For the same reason, it will not be necessary to consider the production of n-p-n, silicon, or high-power transistors. The descriptions which follow therefore apply to germanium p-n-p transistors in general, and in particular to small-signal r.f. and a.f. transistors and medium-power output transistors.
   Thus the present article will be concerned primarily with the OC44 and OC45 r.f. transistors; the OC70 and OC71 a.f. transistors; and the OC72, OC78 and OC81 a.f. output transistors. To cover the production of a range of transistors it is necessary, of course, to concentrate on those processes which are common to all the types.

Fig. 1
  The a.f. transistors just listed - the OC70, OC71, OC72, OC78 and OC81 - have a similar basic construction, the cross-section of which is represented diagrammatically in Fig. 1. The base layer is square or rectangular. The construction of the OC44 and OC45 differs from this in that the base wafer is round and the connection to the base layer is made by a ring-shaped tab which surrounds but does not make contact with the emitter pellet.
   These basic constructions, although at first sight comparatively simple, involve many complex techniques, many of which in the past have been confined to the research laboratory. These intricate laboratory processes are now applied to quantity production in the Mullard transistor factories.
RAW MATERIAL


  The most important raw material used in transistor manufacture is germanium. There are several interesting sources of this rare metal.
  Germanium is present in small proportions in the copper-bearing ores of the Katanga region of the Congo. It also occurs associated with zinc in S.W. Africa. Another source, and not the least romantic, is the flue dust produced by burning Northumbrian coal.
   Northumbrian coal contains about 0.02% of germanium. This is equivalent to about 1 ounce in 3 cwt. Burning the coal acts as the first stage in the extraction, the resulting flue dust sometimes being as much as 1 to 2% rich in germanium.
   The subsequent extraction of the germanium follows normal industrial-chemical practice. The germanium comes to the transistor factory in the form of germanium dioxide-a white powder. By heating the germanium dioxide for several hours in an atmosphere of hydrogen gas, the powder is reduced to the metal germanium.
HIGH DEGREE OF PURITY
  Chemical analysis would show the resulting germanium to be quite pure. But for transistor manufacture, a degree of purity higher than for any other manufactured article is required.
   Traces of impurity have an all-important effect on the conductive properties of germanium. The nature of the impurities and their concentration in the germanium have to be rigorously controlled. Otherwise the electrical properties will be unpredictable, and the germanium will be unsuitable for transistor manufacture.
   The purification is completed by a process known as zone refining. The refining is continued by this process until the impurities with electrical activity are reduced to the order of one part in ten thousand million-1 in 10^10. Put the other way, the germanium is 99.999 999 99% pure.
   This degree of purity was unheard of in metal working before the development of semiconductor devices. The impurity level, which is right outside the range of chemical analysis, is tested by checking the resistivity of the material.
ZONE REFINING
  The ultimate degree of purity is achieved by zone refining. This process is based on the fact that impurities will concentrate more readily in the molten rather than in the solid metal. The zone refiner consists of a silica tube surrounded at intervals by r.f. heating coils. The bar of germanium, after being etched in chemicals to remove the scale from the outside, is placed in a graphite boat and inserted into the zone refiner.
   The graphite boat containing the ingot of germanium is drawn slowly through the tube. Each r.f. heating coil heats up the graphite boat by induction, and thus creates a zone of molten germanium. As the ingot passes through the coils, the zones travel the length of the bar. The impurities collect in the molten zones and are swept to one end of the bar.
  The principle of the process is illustrated in Fig. 2, which for the sake of simplicity is drawn for only one molten zone.

Fig.2
RESISTIVITY CHECK
  The purity of the germanium is checked by measuring its resistivity. A small flat is ground along the length of the bar.
   Along this flat the resistivity of the bar is measured, centimetre by centimetre. The measurement is made by means of a probe having four prongs. The two outer prongs apply a known current, and the voltage drop is measured across the two inner ones.
   The greater the amount of impurity, the lower the resistance. At the end of the ingot containing the impurities from the zone refining, the resistance drops considerably. The point at which the resistance becomes too low is marked on the bar, and this end is cut off by a diamond-impregnated wheel and discarded.
LEVELLING
  The initial purification is designed to eliminate unwanted imperfections from the lattice. Subsequent doping ensures that the imperfections are only such as to give the required p- or n-type conduction.
   The germanium in the ingot will eventually be formed into the base wafers of p-n-p transistors. Consequently this germanium needs to be made n-type, so that it will have free negative carriers.
   A known concentration of antimony must therefore be added to the germanium in the bar. The concentration of the antimony is to be about 1 part in 10^8. The process of introducing the antimony is known as levelling. This process is modified in such a way that the germanium is at the same time re-crystallised as a single crystal.
   The ingot of germanium as it comes from the zone refiner consists of many small crystals of different sizes, the axes of which are arranged at random. It is poly crystalline. Any sample taken from the ingot will consist of pieces from various crystals. Unwanted imperfections would therefore be present in the sample at the boundaries between the crystals.
   For consistent electrical properties, the ingot has to be transformed into a single crystal. To perform the combined operations of levelling and recrystallisation, the rod of pure germanium is placed in a silica boat lined with graphite. A short length of single-crystal germanium, produced during a previous refining, and known as the seed, is placed at one end of the rod. Between the seed crystal and the rod, small weighed pellets of antimony are inserted.
   The levelling and recrystallisation now proceeds by a process similar to zone refining, but using only one molten zone. The metal in the boat is heated by the currents induced in a ring of graphite. As the boat is drawn through the heated zone, a single crystal of germanium grows from the seed. By choosing the right width and speed for the zone, the antimony becomes evenly distributed throughout the length of the bar.
   A single crystal of n-type germanium is produced in this way. It is extremely hard, almost as hard as glass, and is usually cut with a diamond. It cannot be scratched with a steel blade. Before the next operation, the mono-crystalline bars are measured for resistivity, again using the four-pronged probe.
SLICING
  The n-type monocrystalline germanium is required in the form of small, thin wafers. At a later stage in the manufacture, the p-type additive (indium) is infused into two regions on opposite faces of the wafer, to form the emitter and collector. The remaining non-infused germanium in the wafer will constitute the base region.
   The base of the transistor has to be extremely thin, and although the effective thickness is governed finally by the depth of infusion of the indium additive (
Fig. 1), it is necessary to obtain thin slices in the first place.
   The rod of n-type germanium is cut into short lengths which are mounted on a plate and waxed to hold them firmly in position. These portions are now cut into sections or slices about half a millimetre thick. The cutter works rather like a miniature bacon sheer, but is equipped with several diamond-impregnated cutting wheels. The crystal is set at the correct angle in the cutter by means of x-rays. The cutting operation is automatic.

Removing slices of crystal after grinding.
LAPPING
  The slices obtained from the cutting machine are separated from each other and the wax is dissolved. The faces of the slices are now ground to remove those parts of the crystal which have been fractured by the diamond cutters. This is the lapping process. Lapping produces an incidental reduction in the thickness of the slices.
   The slices are separated by spacers in the lapping machines and are ground by successively finer abrasives. After lapping, the resistivity of the slices is measured, and they are sorted into groups suitable for various transistor types.
 
Measuring the resistivity of germanium slice.
DICING

Slices of germanium are seen here being cut into small
circular wafers by an ultrasonic drill. The wafers,
after they have been etched to reduce their thickness
still further, will form the base region of transistors.
  The cross-sectional area of the slices is quite large. Each slice, in fact, is cut up to form a large number of base wafers.
  The base wafers are square, rectangular or round, according to the type of transistor being made.
  Square or rectangular wafers are required for the small-signal and medium - power a.f. transistors. For the OC81, the wafers have to be 2.4 x 2.4 mm, that is, about a tenth of an inch square.
  The cutting of the slices is known as dicing. The slice passes under diamond cutters which score a parallel set of grooves on it. The slice is turned automatically through 90° at the end of the run. On the return journey, more score marks are made at right angles to the first marks. The resulting criss-cross of grooves, rather like those on a bar of chocolate, allows the slice to be separated easily into single wafers.
  Round base wafers, 1.45 mm in diameter, are required for the OC44 and OC45 production. These wafers are obtained from the slices by means of an ultrasonic drill fitted with a perforated bit.
ETCHING
  The final reduction in the thickness of the base wafers is made by etching. The wafers are placed in a small polythene basket with numerous small holes in its side and bottom, and the basket is agitated in the etching fluid.
   After this first etch, the wafers are automatically coarse-graded into batches according to their thickness. Each batch is then re-etched for a period of time depending on the average thickness of the wafers in the batch.
   After the second etch, the wafers are fine graded. Further corrections to the thickness are not carried out by etching, instead, in the subsequent alloying, the temperatures of the furnace are adjusted to suit the average thickness of the wafers in each of the fine grades.
   The thinnest base wafers are those produced for the OC44 and OC45.These wafers are only 100 µm thick - a tenth of a millimetre. At this still quite early stage in manufacture, the dice are worth more than their weight in gold.
PELLETS

  To form the p-type emitter and collector regions, pellets of a p-type additive have to be fused to each side of the n-type base wafer. The p-type additive chosen is indium.
   Indium is a silvery metal, classed as a rare metal like germanium, and sufficiently soft to mark paper as do lead and graphite. Indium wire or strip is cut into portions containing the amount of material required for the pellets. The pellet which forms the Collector is three to five times the size of the one used for the emitter, according to the type of transistor.
   The process for shaping or 'balling up' the pellets bears some resemblance to that used for making lead shot. The pieces of indium are dropped down a glass tube about three feet high and filled with liquid. At the top the liquid is sufficiently hot to melt the pieces of indium into droplets. Further down the liquid is cooler and the drops of indium solidify into spherical pellets.

ALLOYING

  The alloying of the collector junction is carried out before that of the emitter junction. The collector pellet, the base wafer, and the base tab, previously tinned, are assembled in a jig. A moving belt carries the jigs through an electric furnace, the temperature of which is higher than the melting point of indium but lower than that of germanium. The molten indium penetrates the germanium to form an alloy of p-type germanium which is in intimate contact with the n-type base material.
   The jigs are now removed from the furnace, loaded with emitter pellets, and passed once more through the furnace.
  The furnace is divided into three temperature-controlled zones, the temperatures being controlled to within ±1°C on temperatures of the order of 650 °C. This close control is necessary because the depth of alloying, and hence the effective thickness of the base, depends on the furnace temperature.
SOLDERING
  Although the germanium wafers with their alloyed pellets can now be considered to be true transistors, many operations remain to be performed before they can be of any practical use.
   The first of these operations consists in connecting the semiconductor material to leads passing through a glass foot by means of jumper wires. The tinned jumper wires have to be soldered to the emitter, base and collector regions of each unit-an extremely critical operation. Even a miniature soldering iron would be difficult to handle on such small components, and might introduce unwanted impurities. Instead, a stream of hot gas often serves as a source of heat. For the assembly of other types, the heat is provided by discharging a capacitor through the jumper wire. To ensure that the jumper wires are attached accurately to the emitter and collector pellets, the soldering is carried out under a microscope.

The job of joining wires to the emitter and collector pellets is so delicate that
binocular microscopes are used. After joining, the devices are hung from a
magnetic conveyor belt in a washing trough for dispatch to the following process.
CLEANSING AND ETCHING
  After the intricate soldering operation, the flux is washed off by de-ionised (and/or demineralised) water, and the assembly is etched. The etching removes surface contamination, and prevents short circuits from occurring across the emitter and collector junctions at the points where the non-alloyed residue in the indium pellets meets the base material.
  The assembly is submitted to a further wash in demineralised water to remove the chemicals used for etching, and then passes through a drying oven.
ELECTRICAL PRE-TEST
  Before the transistors are encapsulated, they undergo an electrical pretest. To prevent contamination, the pre-test is made in a hermetically-sealed dry box containing a nitrogen atmosphere of controlled humidity.
ENCAPSULATION
  The transistors are now ready for placing in their glass bulbs. The envelopes are first filled with a special silicone compound which will protect the transistor from moisture and help to conduct heat away from the semiconductor material.
   The seal between the glass bulb and the foot is made either by electrically generated radiant heat, or by a gas flame on equipment looking like a scaled-down valve-making machine.
LEAK TEST
  Sample transistors are double tested for ineffective seals. In the first leak test, the transistors are submerged in a mixture of methylated spirit and red dye. The penetration of the red dye into the envelope reveals transistors suffering from gross leakage.
   The second leakage test is really a tropical test, to which again sample transistors are submitted. The test lasts three days, during which the transistors are subjected to three on/off cycles of high temperature and high humidity. If the envelope is at all leaky, the performance of the transistor will deteriorate markedly and it will be rejected at the final electrical test.
   It only remains for the bulb to be painted, or fixed in a metal can, and for the type number and other marks to be applied. Although the spacing of the leads indicates which is for the emitter, base or collector, a coloured spot is placed on the case opposite the collector lead for greater ease of identification.
QUALITY CONTROL
  A comprehensive system of quality control is applied throughout the manufacturing process. On completion, the transistors undergo a series of exhaustive tests. In this way, Mullard engineers ensure that only transistors of the highest quality and reliability reach the consumer.
RESULTS AND DISCUSSION
Among semiconductor devices, the bipolar junction transistor is the most sensitive to material quality andprocessing defects. Therefore, the bipolar transistor, along with p-n junction diode, was fabricated on SOI substrate in order to use different dopant of solid-state source diffusion such as Boronplus and Phosphorusplus concentrations using deposition and derive-in process at room temperature. After fabrication, device was tested using an HP- 6629A semiconductor parameter analyzer with a probing station. The diode was tested first to ensure the transistor operation. It is important to test the performance of the diodes fabricated in SOI wafer since p-n junctions are so
widely used and the SOI substrate material quality can be evaluated by these pn junctions. A typical forward bias IV curve for the SOI emitter-base diode, with collector open circuited.



The semiconductor characterization tool developed here is seen to be capable of a wide range of measurements on simple devices such as p-n junction diode back to back which is called bipolar junction transistor. This paper work is shown the fabrication steps by using diffusion of solid- source- diffusion. The sample of silicon-on-insulator wafer semiconductor p-n junction diode is fabricated with different dopant of solid-state source diffusion such as boron plus and phosphorus plus concentrations using deposition and derive-in process at room temperature. The base is p-type semiconductor and the emitter is n-type semiconductor. Current -voltage measurements are done and the sample has rectifying behavior demonstrated clearly by the I-V curve.

 I-V curve

ACKNOWLEDGEMENT
This work was supported by the grant of the Collaboration between the Microelectronic Design Excellence
Center, Engineering Campus and the Nano-optoelectronics Research Laboratory, School of Physics, all of Universiti
Sains Malaysia. The authors would also like to express their appreciation for the support from the school of
electrical and electronic engineering and school of Physics, Universiti Sains Malaysia.
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