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   The basic requirements to parameters of ESD protection devices

Cost (low as far as it is possible)
Case (small as far as it is possible)
Level ESD (high as far as it is possible)
C load (low as far as it is possible, cannot mention normal function of system)
Jump voltage (low as far as it is possible, but should be> VDD)
Electrical pressure of closure (low as far as it is possible, but should be> VDD)
Leakage current (low as far as it is possible)
 

   Designation and abridgement

-VB - a shorting voltage of the diode at the given level of a reverse current;
- VR-a constant reverse voltage on the diode;
- VF-a constant forward voltage of the diode at a set value of a forward current;
- VESD-an electrical pressure describing stability of die to ESD;
-IR - a leakage current of the diode (reverse current) at the given reverse voltage;
-IF - a forward current of the diode;
-Iрр - the peak not iterating peak reverse current with a pulse shape specified by the international electro technical commission standard IEC61000-4-5. See fig. 1.
рр - the peak not iterating peak power at action of an impulse of currentIрр;
-VCl - an electrical pressure of restriction at the given currentIрр;
-rdiff an incremental resistance of the diode at a set value of a current;
- R-resistance of the resistor in C-R-C filter;
- C - capacity of capacitor (or an input capacitance) in C-R-C filter;
-TJ an operating temperature of transition;
- ESD - the electrostatic discharge;
-ESD HBM-the electrostatic discharge on a model of a human body.
- mil - 1/1000 share of inch (1mil=25,4um).
 
Classification of TVS diodes, TVS arrays and C-R-C filters produce by JSC " VSP-MIKRON ".
Depending on specification applications and mechanically - technological features TVS diodea, TVS arrays and C-R-C filters are classified on 4 series:
а) Series SM-XXYZZ or SM-XX:
- A SM-series of dice of the unidirectional TVS diodes intended for protection of one communication link (with one avalanche diode);
-XX - a rating value of an operating voltage in volts;
- YZZ-the letter of the Latin alphabet and one or two numerals describing distinctive features (alternatives) of die modification.
For example: SM-05L2 - a die of series SM with an operating voltage of 5 volts of modification L2.
Application diagram of TVS diode is shown on fig. 1.
Fig. 1.

b) Series SMB-XXYZZ or SMB-XX:
- SMB - a series of die of the bidirectional TVS diodes intended for protection of one communication link and incorporating two avalanche diodes;
- XX-a rating value of an operating voltage in volts;
- YZZ-the letter of the Latin alphabet and one or two numerals describing distinctive features of die modification.
For example: SMB-05L12 - a die of series SMB with an operating voltage of 5 volts of modification L12.
c) Series KS-XXVYZZ or KS-XXVY:
- KS - a series of die of the unidirectional TVS arrays intended for protection of two and more communication links (the quantity of avalanche diodes in a die coincides with quantity of communication links);
- XX- rating value of an operating voltage;
- V- volt;
- Y-quantity of protected communication links;
- ZZ-the letter of the Latin alphabet and one or two numerals describing distinctive features of modification of a die.
 
For example: KS-5,0V4L1 - a die of series KS with an operating voltage of 5 volts on 4 lines of protection, modification L1.
 
d) Series KSR-XXVYZZ:
- KSR-a series of die of unidirectional TVS arrays with the small size, intended for protection of one or several high-speed communication links;
- XX-the rated operating voltage;
- V- volt;
- Y-quantity of protected communication links;
- ZZ-the letter of the Latin alphabet and one or two numerals describing distinctive features of modification of a die.
 
For example: KSR-3,3V4M1 - a die of series KSR with an operating voltage 3,3 volts on 4 lines of protection, modification M1.
 
Classification C-R-C filters.
 
C-R-C filters are classified on two groups, depending on specification applications and mechanically - technological features dice:
- Filters with a non-central input terminal;
- Filters with a floating input.
Filters of the first group have not the symmetric input volt-ampere characteristics and consequently used in lines with the positive polarity of a feeding electrical pressure concerning ground. The basic electrical diagram for one line of such filter is shown on fig. 2. 
Filters of the second group have a floating input and can use in lines with any polarity of a feeding electrical pressure. The basic electrical diagram of one line is shown on fig. 3.

Non-central C-R-C filters of series EMI-3XXYY:
- EMI-a label of die C-R-C filter intended for inhibition electromagnetic disturbances (and including radio-frequency);
- Numeral 3 the performance of complexity filter design (3-quantity of the fissile and passive components in filter on one line), indicating its accessories to group non-central;
- XX-quantity of protection lines;
- YY - alternative of modification.
For example: EMI-304M1 - non-central C-R-C filter with three constructive devices in each of four lines of modification 1.
 
Symmetric C-R-C filters of series EMI-6XXYY:
- EMI-a label of die C-R-C filter intended for inhibition electromagnetic disturbances (and including radio-frequency);
- Numeral 6 - the performance of complexity filter design (6-quantity of the fissile and passive components in filter on one line), indicating its accessories to group of the symmetric;
- XX-quantity of protection lines;
- YY - alternative of modification.
For example: EMI-602M2 - the symmetric C-R-C filter with six constructive devices in each of two lines modification 2.
 
Basic technical parameters for TVS diodes, TVS arrays and C-R-C filters
- Unidirectional and bidirectional (symmetric);
- The rated operating voltage:
- From 2,8V up to 24V for TVS diodes, TVS arrays;
- 5,0V - for C-R-C filters;
- A leakage current (on ground) - no more 10µА;
- The peak power at tp=8/20µS - from 20 up to 500W;
- The peak current at tp=8/20µS - up to 24А;
- Quantity of protected communication links - от1 up to 10 lines;
- The complete input capacitance (concerning ground):
        а) standard terminators - from 50 up to 200pF;
         б) TVS diodes, TVS arrays and filters with low capacity - from 0,5 up to 45pF.
- A rating value of resistance of the resistor in C-R-C filters - from 10 up to 200 ohm;
- Permissible scatter of resistor resistance - no more +/-20 %;
- The peak junction temperature - Tj=150ºC.
 
Electrical parameters are proving by sampling test in standard conditions (ТА=25ºС) on basic parameters: VB,IR,VF, R. Sample size-150÷300 dice on each wafer with good yield 95 %. If good yield lees then 95% then make 100 % testing control electrical parameters for the probe station. Conformity of other requirements parameters of specifications is secured by a design of dice.
After testing electrical parameters make wafer visual control. Good yield after wafer visual control should be 95 %. If good yield lees then 95% then make 100 % wafer visual control with marking of defect dice.
The dice which are taking place in 3 mm from edge of wafer are not taken into account at sampling test electrical parameters and wafer visual control and not use in assembly of devices.
JSC " VSP-MIKRON " produce and deliver dice of TVS diodes, TVS arrays and filters in wafer form, diameter 4”. Thus the opportunity of a select of alternative modification of some types dice series SM-XX is given users depending on a used method of assembly device:
а) Die with Al metallization top side - for assembly in case of interior terminating connections by a method of ultrasonic welding;
б) Die with structural metallization of top side Al-Ni-Ag-for assembly in a case a solder technique with application PbSn of solders.
 Metallization of back side-Ti-Ni-Ag allows to assembly die on the frame a solder technique with application PbSn of solders.
 

   Packing and storage dice in wafer form

Dice in wafer form are packed in polypropylene cases. Wafers are stacked in a case through interleafs from not dusting substance and through everyone 5 wafers are laid by interleafs from foam rubber. In each case is put the packing label, on this label is specified device type, Lot number, quantity of wafers and quantity of good dice, and also complete list of wafers with the direction of their numbers and quantities good on each wafer.
Each case is located in a polyethylene package from which is exhausted air. Further the package is soldered and the packed wafers are stored in vacuum with the purpose of maintenance high consumer properties during transportation and at storage in warehouse requirements for a long time.
Warranty period of storage of wafers without infringement of vacuum packing - one year. After baring vacuum packing a wafer should be stored in a checked atmosphere of the drained nitrogen and within no more than 30 day should be triggered in manufacture and pass operation of hermetic encapsulation (seal hermetically in case or are filled with an armor coat of compound).
If a warranty period of storage was infringement then wafers should be to additional testing for an estimate of an opportunity their use in manufacture with any finishing or without those.
 

   Directions for application

1.       Baring vacuum packing and a case with wafers should be led in clean working room of class 100000 and higher, with parameters of a microclimate in working band: Т=23 +/-5ºС and damps of 45+/-5 %.
2.       Wafers of TVS diodes, TVS arrays and C-R-C filters to thin abrasion method of to thickness 130÷250um. Therefore they very fragile and demand careful and snug accessing to themselves. With the purpose decrease of probability wafers break at their congestion from a case in transport holders it is recommended to remove a cover and to upturn a case upside down on a planar surface (on a table). Then snug to lift a housing of a case, voiding thus wafers together with foam rubber and impregnated-paper interleafs. Now it is possible to take wafers with to use the vacuum pencil and to transfer them to the transport holder. After removal of a cover expediently to put on its place a flat wafer from any substance for exclusion of opportunity dropout sheets a case during its upturning.
Application of pincers with the mechanical pickup extremely is not desirable in connection with high probability of occurrence flaws and having chopped off.
3. Cutting wafers into dice is recommended to be led a method of disk cutting by the diamond disks providing breadth cut 25-35um, with the subsequent wash in flowing demonized water. Wash should provide the complete removal of yields of cutting from a surface of dice.
4.       Die mounting on the frame is recommended to be led a solder technique with application of solders or solder paste on bottom Pb/Sn in a protective atmosphere of hydrogen or forming -gas (N2+H2 with content H2 not less than 5 %). Application of a method of vacuum brazing also is possible. The peak temperature during soldering dice should not exceed 420 ºС. Cure time of dice at the peak temperature should be minimized for prevention of change specification parameters. The frame before soldering should be stripped of foreign matters and oxide films by a chemical method or annealing in hydrogen medium.
             Analogous recommendations are spread and to process of assembly dice with silver metallization top side.
5.   For dice with Al metallization top side installation of interior terminating connections is recommended to be led a method of welding gold wire diameter 25um. The quantity of wire is recommended to be optimized depending on the sizes of a bonding pad and specification requirements to parameters of the device (Vcl, Iрр). Thus it is necessary to take into account that the increase of quantity wire allows to improve a current distribution on the area of a die and due to it to improve parametersVcl, Ipp. Besides the increase of quantity wire with decrease of their diameter allows to lower probability of origination of mechanical electrical pressure and microcracks in a place of welding. Thus the probability of damage and degradation P-N transitions is reduced. Increase reliabiluty of device.
6.   Before assembly should be stripped of foreign matters and is annealed 2-3 hours at 150ºС for removal of a moisture from a die surface. At assembly in not a die it is recommended to cover the hermetic enclosure silicon with an armor coat. Sheathing process should be in an atmosphere of the drained nitrogen. 
 
Application of ESD protection devices are following: