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SSR / Heat Sink Assembly Design

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1 SSR / Heat Sink Assembly Design
Product Presentation GN SERIES SOLID STATE RELAYS SSR / Heat Sink Assembly Design Return to Main Menu

2 Crouzet Innovation In Solid State Technology
Technology Plus The Technique Innovation In Solid State Technology

3 Features Ratings to 125 Amps / 660 Vac Direct Bond Copper Substrate
Improved Power Lead Frame Design Input Status LED Indicator Surface Mount Technology Cast Base Plate EMC Compliant ( Level 3 ) Internal Transient Protection Larger SCR Die Optional IP20 Touch Safe Housing UL / cUL / CSA Recognized, TUV Approved, CE Compliant

4 Objectives Develop a solid state relay that utilizes the latest technology and has as many features as possible incorporated into the initial design. Design a back-to-back SCR assembly with a thermal efficiency that is significantly better than our competition’s relays. Achieve level 3 compliance with all of the standards set forth by the European Communities EMC Directive. Automate the assembly line to increase reliability and to reduce manufacturing time. Develop and implement automated test procedures that verify the integrity and functionality of the SSR. All of these objectives were met before the GN SSR’s were introduced into the market.

5 Competetive Analysis GN v. Crydom?? Click Here GN v. Carlo Gavazzi??
GN SSR Feature Crydom Teledyne Carlo Gavazzi Continental Current Ratings to 125 Amps Direct Bond Copper substrate EMC Compliant (Level 3) Standard Internal Transient Protection “Bussed” Power Lead-Frame Cast Base Plate LED Input Status Indicator Surface Mount Design Optional IP20 “Touch-Safe” Housing Comparison against Crydom HA/HD Series, Teledyne SSR Series, Continental SV Series, and Carlo Gavazzi RM Series Yes No *No *Teledyne uses exposed ceramic substrate as base plate No Yes **Yes **Snap-on protective cover included with the Carlo Gavazzi RM Series SSR Yes No No Yes

6 Thermal Derate Information ?? Click Here
Thermal Efficiency Heat is the primary cause of SSR failures in most applications. As current flows through the relay, the SCRs generate heat which must be dissipated through the ceramic substrate, through the base plate, and into the heat sink. The heat sink is then cooled by the ambient air. The SSRs ability to function reliably in an application is dependent upon how well it can transfer heat from the SCR die to the heat sink. If the SSR is not very efficient in transferring heat through the base plate, then the size of the heat sink must be increased to compensate for this or the relay and/or load may be damaged. SSR thermal efficiency is measured in degrees Celsius per watt being generated by the SCRs, or Rjb. The lower the SSRs Rjb rating, the more efficient it is. Rjb is determined by the type of ceramic substrate used, the thickness of the ceramic, and how well the SCR die and substrate are assembled. Thermal Derate Information ?? Click Here

7 Direct Bond Copper SSR Rjb Comparison
Direct Bond Copper (also known as Direct Copper Bonding or Fused Copper) has a much lower thermal impedance than traditional foil substrates. The ceramic and copper are heated and pressed to form a “bond” which minimizes the thermal barrier between the traces and the substrate. The GN series SSRs also utilize a substrate that is 40% thinner than traditional ceramic substrates, making the SSR even more efficient. SSR Rjb Comparison Rjb Rating - ºC/W 10Amp 25Amp 50Amp 75Amp 100Amp 125Amp Carlo Gavazzi RM Series Crydom HD Series Teledyne SSR Series N/A 0.80 0.50 0.20 1.48 1.02 0.63 0.31 0.28* 0.22 0.40 0.35 0.30 0.25 Crouzet GN Series 0.155 0.15 *Rjb rating for 100A applies to Crydom 90A SSR’s

8 GN SERIES SOLID STATE RELAYS
“Bussed” Power Lead Frame Direct Bond Copper Substrate Cast Base Plate

9 Reliability Surface Mount Components EMC Compliance Epoxy-Free Design
Reduces the possibility of human error in component placement and soldering. EMC Compliance Allows the SSR to operate normally in harsh electrical environments without being damaged or creating electrical noise that might interfere with ancillary equipment. Epoxy-Free Design Eliminates the possibility of components becoming damaged due to the encapsulation expanding and contracting as the relay is heated and cooled. Also reduces capacitive coupling between the input and output circuitry that may allow a relay to be more susceptible to electromagnetic interference. The PCB is covered with a conformal coating to prevent the ingress of dust or moisture and to maintain dielectric strength Automated Test Equipment In-process test equipment automatically verifies critical parameters and separates any rejected unit from the good units. A proprietary thermal impedance measuring system, called the “Delta Vf” test, verifies the integrity of the SCR assembly. X-ray equipment is then utilized to corroborate the results.

10 GN SERIES SOLID STATE RELAYS
Regulated AC & DC Inputs VDE Approved Optical-Isolators Internal Transient Protection

11 Electromagnetic Compatability
Electrical transients, voltage and current surges, electrostatic discharges, conducted and radiated interference, and line voltage fluctuations, are all phenomena that frequently occur in industrial and commercial environments. Placing a product on the market that will operate normally in this type of environment is essential for reliability. The GN Series SSR’s have been designed and evaluated for compliance with level 3 requirements of the European Union’s EMC Directive. This has resulted in a relay with enhanced reliability that can facilitate an OEM’s evaluation for EMC compliance. It also eliminates the need for external transient protection, such as MOV’s.

12 Applications Typical Applications for the GN Series SSR’s
Theatrical Lighting Systems Warehouse Lighting Systems Plastics; Injection, Blow Molding, Extrusion and Thermoforming Equipment Solder Reflow Systems Rotisserie Ovens Deep Fat Fryers Packaging Equipment Industrial Electric Furnaces Conveyer Systems Material Handling Equipment Compressor Systems Medical Equipment Vending Machines Uninterruptible Power Supplies Copy Machines Welding Equipment Water Treatment Systems Virtually any manufacturer of electrical equipment switching current in excess of 1 amp may utilize solid state relays.

13 SSR Selection GN Part Number Matrix:
To better enable Crouzet in helping you select the right relay, obtain as much information as possible about the application before calling for assistance. A few key questions to ask include: Line Voltage Ambient Temperature Inside Panel Load & Steady-State Current Type of Load & Duty Cycle Control Voltage Available Cabinet Space Mounting Requirements Airflow (Forced or Convection GN Part Number Matrix: Package Style: Output Type: Current: Control Voltage: 84 134 1 2 = IP00 = IP20 0 = Vac / Zero Cross 1 = Vac / Zero Cross 2 = Vac / Random 3 = Vac / Random *9 = Vac / Triac Output 0 = 10 Amps 1 = 25 Amps 2 = 50 Amps 3 = 75 Amps 4 = 100 Amps 8 = 125 Amps 0 = 4-32Vdc **1 = Vac **2 = 18-36Vac *Triac version available with only 10 & 25 amp output **AC input available with only zero-crossing output

14 GN SCR Assembly v. Traditional SCR Assembly

15 GN PCB Assembly v. Traditional PCB Assembly

16 GN Series SSR's Heat Sinks & Custom Assemblies
The Next Generation of Solid-State Relays Heat Sinks & Custom Assemblies

17 HS-3 1.5ºC/W Heat Sink Single Phase SSR’s

18 HS-4 1.0ºC/W Heat Sink Single Phase SSR’s

19 HS-7 0.9ºC/W Heat Sink 1 Three Phase SSR, 1-4 Single Phase SSR’s

20 HS-8 2.1ºC/W 45mm Din Rail Heat Sink Single Phase SSR’s
Crouzet “Smart Module” mounted to GN Series SSR

21 HS-9 1.3ºC/W 90mm Din Rail Heat Sink
1-2 Single Phase SSR’s

22 HS-12 0.5ºC/W 60mm Din Rail Heat Sink Single Phase SSR’s
Manual Reset Thermal Cutout 60mm 22CFM Fan

23 CROUZET Solid State Relays Digital I/O Modules Proximity Sensors
I/O Mounting Boards Safety Relays Sub-Fractional H.P. Motors Industrial Counters Miniature Snap Action Switches Limit Switches Industrial Timers Axial Fans For technical assistance, pricing & availability, call

24 SSR / Heat Sink Assembly Design
GN SERIES SOLID STATE RELAYS SSR / Heat Sink Assembly Design Return to Main Menu

25 CROUZET V. CRYDOM SOLID-STATE RELAYS

26 CROUZET CRYDOM GN SERIES SSR's v. HA/HD SERIES SSR's
RATINGS TO 660VAC / 125A DBC SUBSTRATE “BUSSED” POWER LEAD FRAME INTERNAL TRANSIENT PROTECTION (standard) EMC COMPLIANT (LEVEL 3) LED INPUT STATUS INDICATOR REGULATED INPUT SURFACE MOUNT PCB OPTIONAL IP20 HOUSING UL/CSA/TUV (VDE) APPROVED, CE COMPLIANT (OPTIONAL) (HD SERIES ONLY)

27 STAMPED ALUMINUM BASE PLATE
PRESS-FIT & SOLDER TERMINALS CRYDOM FORM & SOLDER LEAD FRAME TRANSISTOR OUTPUT OPTICAL ISOLATORS THICK-FILM CERAMIC SUBSTRATE STAMPED ALUMINUM BASE PLATE

28 CROUZET TRIAC DRIVER OPTICAL ISOLATORS LED INPUT STATUS INDICATOR
INTERNAL TRANSIENT PROTECTION

29 CROUZET DIRECT BOND COPPER (DBC) SUBSTRATE “BUSSED” POWER LEAD FRAME
CAST BASE PLATE

30 GN SERIES SSR PRESENTATION
Return to Main Menu

31 CROUZET V. CARLO GAVAZZI SOLID-STATE RELAYS

32 CROUZET CARLO GAVAZZI GN SERIES SSR's v. RM SERIES SSR's
RATINGS TO 660VAC / 125A DBC SUBSTRATE “BUSSED” POWER LEAD FRAME INTERNAL TRANSIENT PROTECTION (standard) EMC COMPLIANT (LEVEL 3) LED INPUT STATUS INDICATOR REGULATED INPUT SURFACE MOUNT PCB OPTIONAL IP20 HOUSING UL/CSA/TUV (VDE) APPROVED, CE COMPLIANT 100 amps max MOV Across Output Clip On UL,CSA,CE

33 CARLO GAVAZZI FORMED & SOLDERED LEAD-FRAME;
POTENTIAL COLD SOLDER JOINT AND STRESS ON DBC SOLDER JOINT CARLO GAVAZZI DIRECT BOND COPPER SUBSTRATE; NOT SOLDERED TO BASE PLATE ON 25A AND 50A MODELS

34 CARLO GAVAZZI SMALLER BASE PLATE REDUCES THE
AVAILABLE SURFACE AREA FOR HEAT TRANSFER

35 CROUZET TRIAC DRIVER OPTICAL ISOLATORS LED INPUT STATUS INDICATOR
INTERNAL TRANSIENT PROTECTION

36 CROUZET DIRECT BOND COPPER (DBC) SUBSTRATE “BUSSED” POWER LEAD FRAME
CAST BASE PLATE

37 Back to the GN SSR Presentation

38 CROUZET CORPORATION SSR Thermal Derating

39 SSR / Heat Sink Assembly Design
Properly derating any SSR-heat sink assembly is critical to the reliability of the assembly and overall satisfaction of the customer. Cost, Size, shape, color, or any other particular requirement, is secondary to insuring that the heat generated by the relay will be adequately dissipated by the heat sink. Lack of attention to detail when designing an assembly may significantly decrease the life of the relay or result in catastrophic field failures. Essential derating information: Additional Helpful Information: Ambient Temperature (Tamb) Air Flow (CFM or LFM) Load Current (I) Duty Cycle SSR On-State Voltage Drop (Vf) Panel Ventilation SSR Thermal Impedance (Rjb) Surrounding Heat Sources Heat Sink Thermal Impedance (Rs-a) Surge Currents

40 Tdie = Tamb + (Rs-a x (I x Vf)) + (Rjb x (I x Vf))
As can be seen from the formula, the temperature of the SCR die during normal operation is a sum of the product of the ambient temperature, heat sink efficiency, SSR thermal impedance, and the total power being dissipated by the relay. If the sum exceeds the maximum temperature rating of the SCRs, which is typically 125ºC, then one or more of the variables must be reduced in order to prevent a failure of the SSR. If the sum is less than the maximum temperature rating of the SCRs, then it is safe to proceed with a verification analysis of the assembly. IT IS ALWAYS IMPORTANT TO VERIFY THE RESULTS OF THE INITIAL ESTIMATE, AS THE VARIABLES ARE NOT ALWAYS 100% ACCURATE!

41 GN SERIES SOLID STATE RELAYS
If we take the formula in steps, we can calculate the temperature of the two “critical” points of the assembly. The first half of the formula, “Tamb + (Rs-a x (I x Vf))”, gives the actual temperature of the base plate of the SSR. The second half of the formula, “(Rjb x (I x Vf))”, gives the temperature differential between the base plate and the SCR die. To fully appreciate all of the variables involved, we must understand the components that make up those variables; GN SSR - SCR / BASE PLATE ASSEMBLY SCR DIE; Switches the load current. The die are soldered to the copper traces on the top-side of the DBC. CERAMIC SUBSTRATE; Provides electrical isolation between the SCR die, which are at line potential, and the base plate of the SSR. The copper traces on the bottom of the DBC are soldered to the base plate of the SSR. COPPER TRACES; The traces are “fused” with the ceramic, forming the DBC substrate. This provides a path for the load current through the SCR die, and allows heat to spread throughout the entire surface of the substrate. SSR BASE PLATE; Transfers the heat generated by the SCR die to the heat sink.

42 Heat Transfer & Thermal Impedances
As the load current flows through the SCR die, heat is generated proportional to the amount of the current and the Vf of the SCRs. The total thermal impedance of the SCR / base plate assembly determines how much of this heat is transferred through the DBC and base plate, and is measured in degrees Celsius per Watt being generated, or Rjb. To calculate the temperature differential, or DT, between the SCR die and the base plate, we multiply the Rjb by the total power being generated. Assume the SSR is carrying 50 amps of load current and has a forward voltage drop of 1.2Vpk. The junction-to-base plate thermal impedance is .155ºC/W We now know that the SCR die are operating 9.3ºC hotter than the base plate of the SSR. Alone, this information is not very helpful, as it only gives us the DT, and not the actual temperature of the SCR die. DT = Rjb x (I x Vf) DT = .155ºC/W x (50A x 1.2Vf) DT = 9.3ºC To determine the actual temperature of the SCR die, we must determine the temperature of the SSR’s base plate. Heat Transfer

43 Base Plate Temperature
Ambient to Base Plate The thermal impedance of the heat sink determines how much the temperature will vary between ambient and the base plate, relative to how much power the SSR is dissipating. Heat sink efficiency is also measured in degrees Celsius per Watt of power, but will change depending upon the ambient temperature and the availability of forced airflow. For applications where the device is to be cooled through convection airflow, the heat sink must be mounted in a manner that will allow air flow to move up through the fins. To estimate the base plate temperature of the SSR, simply multiply the heat sink impedance by the total power being dissipated, then add the sum to ambient. Assume the SSR is carrying 50 amps of load current and has a forward voltage drop of 1.2Vpk. The thermal impedance of the heat sink is 1.0ºC/W and Tamb is 40ºC Base Plate Temperature Tbp = Tamb + (Rs-a x (I x Vf)) Tbp= 40ºC + (1.0ºC/W x (50A x 1.2Vf)) Tbp= 100.0ºC Tamb = 40ºC Convection Airflow

44 SCR Assembly; 0.155ºC/W Rjb, 1.2Vpk Vf
Ambient to SCR Die Since all of the variables are now known, we can estimate the temperature of the SCR die in an SSR with an Rjb of .155ºC/W and a Vf of 1.2Vpk, operating at 50 amps while mounted to a 1.0ºC/W heat sink. Tdie = Tamb + (Rs-a x (I x Vf)) + (Rjb x (I x Vf)) Tdie = 40ºC + (1.0ºC/W x (50A x 1.2Vpk)) + (.155ºC/W x (50A x 1.2Vpk)) Tdie = 40ºC + 60ºC+ 9.3ºC Tdie = 109.3ºC To be even more accurate, we should include the thermal pad, which has a thermal impedance of approximately 0.1ºC/W. Tdie = 109.3ºC + (60W x .1ºC/W) Tdie = 115.3ºC SCR Assembly; 0.155ºC/W Rjb, 1.2Vpk Vf Thermal Heat Sink Compound or Thermal Pad 1.0ºC/W Heat Sink Tamb = 40ºC Convection Airflow

45 Now that we have determined that the SCR die should operate at less then their maximum rated temperature, a quick thermal analysis of the assembly must be performed to verify the accuracy of the calculation. This is important since any deviation in one or more of the variables will lead to significant differences between the calculated and actual die temperature. Since it is not always feasible to attach a thermocouple to the die of an SSR, temperatures can be measured at the base plate of the SSR to verify the accuracy of the estimate. Unfortunately, this method still leaves a level of uncertainty in the analysis since we must calculate the differential between the die and the base plate. However, as this calculation has the least impact in total temperature rise, and given the accuracy of measured power over estimated power dissipation, the end result will be fairly accurate. To guarantee reliability, never let the base plate exceed 100ºC and allow the SSR to stabilize for a few hours before taking the final measurement!! Thermocouple inserted into a groove milled in the top of the heat sink. The groove should be slightly larger then the diameter of the TC to allow the SSR to mount flush with the heat sink. Tdie = actual base plate + (specified Rjb x actual power)

46 Forced Air v. Convection Cooling
Calculating the thermal impedance of a heat sink with forced air is a little more difficult since there are a few more variables and intangibles involved. There is, however, a simple formula that can give an estimate of the thermal impedance, which can then be verified through evaluations. For simplicity, let’s assume that there is minimal obstruction to the airflow and that the “open” area in the heat sink is roughly the same size as the area of the fan. First, we must convert the CFM rating to linear feet per minute (LFM); LFM = (CFM / (area / 144)) x 70% (70% derate for back pressure) Forced Vertical Airflow LFM = (40 / (9 / 144)) x .7 LFM = (40 / .0625) x .7 LFM = 448 (Derate down to 400LFM) Once the approximate LFM rating is known, a correction factor can be applied to the heat sink to determine the thermal impedance with airflow. 1.0ºC/W Heat Sink (Convection) Velocity (LFM) Correction Factor 1, (1.0ºC/W x .378) So our heat sink would have a .378ºC/W thermal impedance with 400 LFM of airflow. 3” x 3” 40 CFM Fan

47 Forced Air Efficiency To demonstrate the increase in the efficiency of the heat sink provided by the 40CFM fan, we can calculate how much more current (I > 50 Amps) the SSR would have to carry in order to obtain the same 115.3ºC die temperature as before. To insure adequate derating, we will round the impedance of the heat sink to 0.4ºC/W. 115.3ºC = Tamb + (Rs-a x (Vf x I)) + (Rjb x (Vf x I)) 115.3ºC = 40ºC + (.4ºC/W x 1.2X) + (.155ºC/W x 1.2X) 115.3 = X X 75.3 = .667X X = Amps (Increase of 62.9 Amps) Always evaluate an assembly that is to be cooled by forced air before the customer begins using the assembly in their production. Forced air cooling systems are tricky at best and SSR failure may result from an inadequate understanding of the systems parameters. Installing assemblies in the customers equipment for thermal testing is the best way to insure overall reliability.

48 Cut-to-Length Extrusions
A standard heat sink profile listed in an extruder’s catalog will typically have the thermal impedance specified when cut to a length of three inches. A rough determination of the impedance of an extrusion profile cut in different lengths can be obtained with a correction factor. Multiplying the Rs-a/3” by the correction factor for the desired extrusion length will give the thermal impedance of that profile when cut to that length. This is a valuable tool when designing prototype assemblies, but the correction factor will vary slightly for each profile due to various spacing and lengths of the fins. A 1.0ºC/W 3” profile cut to a length of 6” would have a thermal impedance of 0.73ºC/W. Extrusion Length Correction Factor 1” 1.80 2” 1.25 3” 1.00 4” .87 5” .78 6” .73 7” .67 8” .64 9” .60 10” .58 11” .56 12” .54

49 2X + 3Y = Z qp pq ¹ E=h x f l = h / (m x v) It's All in the Math
To Calculate SCR Temperature: Tdie = Tamb + (Rs-a x Power) + (Rjb x Power) Tdie = Tbp + (Rjb x Power) To Calculate Heat Sink Thermal Impedance: Rs-a = (Tbp - Tamb) / Power Rs-a = ((Tdie - (Rjb x Power)) - Tamb) / Power qp pq To Calculate Minimum Required Heat Sink Thermal Impedance: Rs-a-min = (Tdie-max -Tamb - (Rjb x Power)) / Power To Calculate Maximum Allowable Current Given Heat Sink Impedance: Imax = (Tdie-max - Tamb) / ((Rs-a x Vf) + (Rjb x Vf)) To Calculate Base Plate Temperature: Tbp = Tdie - (Rjb x Power) Tbp = Tamb + (Rs-a x Power) E=h x f To Calculate Rjb: Rjb = (Tdie - Tbp) / Power l = h / (m x v)

50 Ambient Might Not Be Ambient
Words of Wisdom Corroborate All Data Always verify any calculation. Catastrophic field failures may occur if the actual value of a variable shifts even a slight amount from the estimate. Evaluate every new assembly in an environment as close as possible to the actual application or in the actual equipment for which it is intended. Derate The Derating Round up every number in the calculations and use maximum value specifications whenever possible. If the test data yields results that are better than originally estimated, and target pricing is maintained, then everyone wins. Ambient Might Not Be Ambient The ambient temperature given by the customer may be misleading. The room temperature outside of the panel, or panel temperature when the system is not running, will not help much when calculating minimum heat sink requirements. Insure that the temperature of the air moving through the fins of the heat sink is the value that is used in the estimates. Expect The Worst If something bad can possibly happen, assume that it will. Loss of airflow, 100% duty cycle operation, heavy surge currents, and excessive ambient temperatures, are just examples of anomalies that may occur in any application. If the customer has experienced them before, then he will most certainly experience them again.

51 Back to the GN SSR Presentation
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