SinkPAD technology provides a direct thermal path between LEDs and their surrounding environment to improve heat dissipation compared to conventional MCPCB boards. It eliminates the dielectric material from the thermal conduction path, reducing thermal resistance. This allows higher power operation of LEDs while maintaining safe junction temperatures. SinkPAD boards are available with aluminum or copper bases and can transfer heat at rates over 200 W/mK, far exceeding conventional MCPCB boards. They provide an effective solution for thermally managing high-power LED applications like lighting.

1. 1
CHAPTER 1
INTRODUCTION
1.1 Basic of SinkPAD Technology:
Light from an LED (light emitting diode) comes from the LED chip within the LED
package. Light output increases with increasing drive current, but in addition to emitting visible
light, the LED chip also becomes hot. This thermal energy limits the amount of power an LED
can ultimately handle and must be conducted away from LED chip and dissipated to surrounding
environment. Light output, light color, lumen maintenance, and LED lifetime are all adversely
affected by excessive LED temperatures during operation. The critical temperature of the LED is
called the LED chip junction temperature (Tj),Tj is a function of such as LED component design
Some LEDs have enhanced thermally conductive lead frames and can handle higher drive
currents and power levels, LED forward current and voltage (this is the power dissipated in the
LED). Higher drive currents result in more power dissipation and higher Tj, pcb design, Thermal
resistances of components in the system and ambient temperature. Good LED product design
achieves a balance between maximizing the light output from the LED while maintaining safe
power and temperature levels in the LEDs and other system components. The designer must
understand the basics of thermal heat transfer, employ proper thermal techniques in the design,
measure the temperature of the LEDs, and reliably control the delivered power.
The PCB used to mount the LEDs is the first thermal conductor in the system, and
frequently has the largest effect on heat transfer from the LEDs to the ambient environment. To
avoid the heating in the LED the newer technology i.e. SinkPAD Thermal Management
Technology is used. SinkPADTM technology significantly improves LED thermal management
in all LED systems. It is most effective in high-power LED cooling, making it possible for
commercialization. SinkPADTM conducts heat out of the LED system by enabling a direct
thermal path between the LED and surrounding atmosphere. The LED thermal resistance can be
substantially reduced by eliminating the lowest thermal conductivity/highest thermal resistance
component, the dielectric material. Unlike conventional MCPCB, the dielectric material in a
SinkPADTM PCB functions only as electrically insulated barrier to the metal base but leaves it
thermally connected, i.e. direct thermal path.

2. 2
1.2 ORGANISATION OF REPORT
Chapter 1: Introduction
Chapter 2: Literature Survey
Chapter 3: System Development
Chapter 4: Working Principle
Chapter 5: Advantages And Disadvantages
Chapter6: Conclusion

3. 3
CHAPTER 2
LITERATURE SURVEY
2.1 HISTORY:
Placentia, California - SinkPAD Corporation has announced its new SinkPADTM*
aluminum PCB technology is now available. CTO Kris VA soya stated “We are up and running,
ready to support our customers with our problem-solving LED thermal management PCBs using
our SinkPADTM technology. We are open for business.” SinkPAD corporation’s new thermally
enhanced PCBs are a complete and effective solution to the challenges faced by the solid state
lighting industry, specifically those with aluminum LED PCB applications. Available now, the
new SinkPADTM technology significantly improves LED thermal management in all LED
systems. It is most effective in high-power LED cooling, making it possible for
commercialization. SinkPADTM conducts heat out of the LED system (LED conduction
cooling) by enabling a direct thermal path between the LED and surrounding atmosphere.
The LED thermal resistance can be substantially reduced by eliminating the lowest
thermal conductivity/highest thermal resistance component, the dielectric material. Unlike
conventional IMS PCB or MCPCB, the dielectric material in a SinkPADTM PCB functions only
as an electrically insulated barrier to the metal base but leaves it thermally connected, i.e. direct
thermal path. The thermal path of an LED should be electrically neutral within the LED package,
i.e. Cree XP, XM-L, MT-G, XR, Luxeon Rebel from Philips Lumiled, Olson SSL from OSARM,
N219 from Nichia, PhlatLight from Luminous etc., in order to solder the LED directly to the
SinkPADTM. To find out how SinkPAD’s technology (LED thermal PCB) can remove the heat
in your LED application, contact SinkPAD Corporation or visit the SinkPAD.
SinkPAD,
LLC is a manufacturer of “Direct Thermal Path” Printed Circuit Boards
(SinkPAD Technology). We also offer conventional MCPCB and FR4 printed circuit boards.
SinkPAD LLC along with its group of companies brings over 40+ years of PCB manufacturing
experience. SinkPADTM
technology address the thermal issues associated with LEDs. We
specifically developed this technology for the Solid State Lighting Industry and it is best suited
for medium to high power LED applications. SinkPADTM
is a thermally superior printed circuit
board technology that will reduce the LED junction temperature with its 200+ W/m.k thermal

4. 4
conductivity and is an alternative technology to the conventional Aluminum PCB or MCPCB
with 2to5 W/m.k. We are headquartered in Southern California (USA).
Fig.2.1 Sinkpad- Aluminum V/S MCPCB Aluminum And Copper
This test data was submitted to SinkPAD by an independent party. The testing was done
on a 21mm star board with a Cree XML LED. SinkPAD Aluminum PCB shows higher light
output than a conventional Copper PCB. All our engineering, sales, warehouse, accounting and
customer service are performed here. We recognize LED market is very cost competitive. In
order to enable our customer stay competitive in market we have established our manufacturing
capability in Asia. SinkPAD, LLC is a growing and innovative company.
2.2 AN OVERVIEW OF EXISTING SYSTEM:
MCPCB, Metal Core PCB, thermal PCB - whichever name you prefer, they are all boards
which use a base metal material as the heat spreader portion of the circuit board. Base metals in
the MCPCB are used as an alternative to FR4 or CEM3 boards for the ability to dissipate heat
away from critical board components and to less crucial areas such as the metal heat sink
backing or metallic core. The metal core of the thermal PCB can be aluminum (aluminum core
PCB), copper (copper core PCB or a heavy copper PCB) or a mixture of special alloys. The most
common is an aluminum core PCB. The thickness of metal cores in PCB base plates is typically
30 mil - 125 mil, but thicker and thinner plates are possible. MCPCB copper foil thickness can
be 1 - 10 oz.

5. 5
Fig.2.2 Metal Core PCB With Aluminum Core Photo Credit: Robert Tazewell
MCPCBs can be advantageous to use for their ability to integrate a dielectric polymer
layer with a high thermal conductivity for a lower thermal resistance. Metal core PCBs
transfer heat 8 to 9 times faster than FR4 PCBs. MCPCB laminates dissipate heat, keeping
heat generating components cooler which results in increased performance and life.
Multiple devices all on the same power on an FR4 0.8mm thick board enhanced with
thermal Viasversus a MCPCB board. Thin (0.15mm) interface material used between the
enclosure wall and the power dissipating board.
Fig.2.3 Metal Core PCB
Applications that generate a large amount of heat often cannot be adequately cooled using
just traditional fans. Conductive cooling through metal core PCBs are an ideal production

6. 6
option. MCPCBs are most widely found in LED technologies, as they reduce the number
of LEDs required to produce a specific illumination. Light emitting diodes release a great
amount of heat in applications such as:
 Back light unit applications
 Street safety applications (streetlights, lighting, etc.)
 General lighting applications
 System automotive LED applications
 Power converters: telecom, industrial, high voltage regulator, power supplies
 Hybrid/electric motor control applications
 Photovoltaic
2.3 AN OVERVIEW OF IMPROVED SINKPAD SYSTEM:
In a LED heat originates at the chip in same way that in normal light bulb heat originates
at the filament. A high rate of thermal conduction means cooler running LEDs while a low rate
means very hot and potentially self-destructive LEDs. If all substances had the same and low
thermal resistance then it would not matter how many mediums heat would have to be conducted
through before it reached the atmosphere.
Since this is not the case, an ideal situation is one in which any substance with a low
thermal conductivity & a high thermal resistance is removed from the conduction thermal path.
These low thermal conduction/high thermal resistance substances slow the transfer of heat and
therefore increase junction, temperature.
Fig.2.4 Sinkpad Metal Substrate Sectional View

7. 7
Typically conventional MCPCBs are commonly used to dissipate heat from a LED to a
heat sink. MCPCB uses a thermally conductive dielectric layer to bond circuit layer with base
metal The key to thermal performance of MCPCB lies in its dielectric layer. Even though
thermally conductive dielectric has higher thermal performance copared to standard dielectric
material it is still a weakest link in the conduction thermal path in the MCPCB.
c
Fig.2.5Aluminum Sinkpad PCB Outperforms Copper MCPCB
SinkPADTM
PCB approach overcomes this limitation and eliminates use of a dielectric
material completely from a conduction thermal path. SinkPADTM
Technology provides “Direct
Thermal Path”, lowering LED junction temperature. SinkPADTM
technology has magnitudes
higher thermal efficiency than even the very best MCPCB in the market. SinkPADTM
MCPCB is
available with Aluminum base metal or Copper base metal. Aluminum based SinkPADTM
PCB
can transfer heat at the rate of 210.0 W/m.K and Copper based SinkPADTM
PCB can transfer
heat at a rate of 385.0 W/m.k. Conventional MCPCBs have a heat transfer rate of 1-5
W/m.k. The way in which we can accomplish this dramatic improvement is by creating a Direct
Thermal Path from the LED to the base metal.

8. 8
CHAPTER 3
SYSTEM DEVELOPMENT
3.1 An Importance Of Thermal Management For High Power LEDs:
Fig.3.1Thermal Management In Sinkpad And MCPCB
LED technology produces a lot of heat that can result in high temperatures. Use of heat
sinks is one way of reducing this temperature by drawing heat away from the LED sourceEmbed
such as:
1. In the recent past, LED technology has seen a wide range of application in home
appliances as well as in industry. High power LED, generates a lot of heat in the process
of application. This is because of the electricity they consume, 70% converts to heat
while the rest converts into light. This heat is not good as it makes the LED to run at high
temperatures. This high temperature affects the LED in two ways.
2. Firstly, the LED will not work as efficiently as they should. The high temperatures affect
the environment in which the LED operates and this causes the LED to work as it should
not. It is therefore important to lower this temperature in order for the LED to work the
way it should.

9. 9
3. Use of Heat sinks: It is therefore important to manage the high temperature in the LEDs
by conducting away the heat generated. There are many ways to do this and one effective
way is by using heat sink for LED. A heat sink provides a path through which the heat
moves from the LED source to the outside medium. The heat sink can use convection,
conduction or radiation to move this heat away from the LED source. When choosing a
heat sink, you need to consider various features for a successful process.
4. Shape and material: When looking for a heat sink, you need to consider a few things in
order to make the thermal management successful. The material used to make the heat
sink will affect how the heat dissipates from the LED source. Aluminium has high
dissipation efficiency and most heat sinks will employ it. Copper is another efficient
material and is applicable for flat-sheet heat sinks. The shape of the heat sink also
determines its efficiency. Since the heat transfer occurs on the surface of the heat sink, it
should have a high surface area. This means the heat sink should have numerous fins or
be large.
5. Surface finish and mounting: The other consideration in thermal management is the
surface finish of the heat sink to use. The type of finish the heat sink has should reduce
the thermal resistance between the LED source and the conductor. The other
consideration is the method you will use to mount the LED heat sink. Heat sink
mountings should utilize either screws or springs as these are better at thermal
management than using glue or tape. The choice of heat sink will therefore play an
important role in efficient thermal management.
6. Thin gauge thermocouple wire (30 gauge or higher). The thermocouple mass should not
be large enough to conduct significant heat away from the measurement point. This is
particularly true of (5 mm) leaded thru-hole LEDs.
7. This is always a good thing, and often times, as an indirect effect the size of the devices
in these applications can also be reduced because of smaller or now non-existent active
cooling systems making these devices cheaper to make and more desirable to the
consumer.

10. 10
3.2 Thermal management for LED:
Fig.3.2 Surface Mount LED With Thermal Vias
For surface mount LEDs, use large copper pads on both sides under the heat sink of the
LED. Connect pads with multiple vias (Fig. 2 above) to conduct heat from one side of the pcb to
the other.
3.2.1 Metal Core Printed Circuit Boards (MCPCB) :
Another type of circuit board is called a Metal Core Printed Circuit Board (MCPCB) that
places an aluminum plate under the dielectric fiberglass layer (Fig 3). This ‘core’ facilitates heat
flow and is often mounted onto a heat sink for use with higher power LEDs.
Fig.3.3 Heat Flow Diagram Of A Metal Core PCB.

11. 11
3.2.2 Measuring LED Temperatures :
Direct contact measurements of the LED junction temperature are not possible because
the LED chip is encapsulated. Instead, thermocouples are commonly used to measure the LED
case temperature Tc (also known as the solder point temperature Ts or temperature measurement
point TMP (Fig. 4)). Tc is specified by the LED manufacturer, and should be close to the LED
chip junction. For through-hole LEDs, the thermocouple measurements will be taken on the lead
that attaches directly to the LED chip.
Fig.3.4 Through-Hole LED With Tj And Tc Location
3.2.3 Thermal Measurement Guidelines:
Good thermal measurement results are vital to proper design engineering. Care must be
taken when making measurements because mistakes will yield temperature readings that are
lower than the actual temperatures.
1) Check thermocouples for accuracy. Use ice water and boiling water to make sure the
thermocouple measures 0 °C and 100 °C, respectively (these values apply at sea level;
adjust as necessary for altitude).
2) Use thin gauge thermocouple wire (30 gauge or higher). The thermocouple mass should
not be large enough to conduct significant heat away from the measurement point. This is
particularly true of (5 mm) leaded thru-hole LEDs.
3) Attach the thermocouple to the LED case location with solder or a thermally conductive
epoxy. Make sure that the head of the thermocouple is in good thermal contact with the
metal lead. Type “T” thermocouples are composed of copper based wires and are easier
to solder than other thermocouple types. Note that electrical noise can sometimes
interfere with a thermocouple measurement.

12. 12
3.2.4 Heat Flow Basics :
Management of heat in LED products requires careful attention to heat transfer
principles. Thermal energy (heat) flows from a hot object to a cool object when the two come in
contact with each other. This is called thermal conduction. . With both processes of convection
and conduction the amount of heat transferred from hot to cold is limited by the surface area of
contact between the hot object.
a. Conduction – transfer of heat through matter by communication of kinetic energy from
particle to particle. An example is the use of a conductive metal such as copper to transfer
heat.
b. Convection – heat transfer through the circulatory motion of a liquid or gas in contact
with a hot surface. Air surrounding a hot object removes heat by conduction and
convection, where gas molecules flow past the surface and remove heat energy.
c. Radiation – energy transmitted through infrared electromagnetic waves. Visible light
LEDs do not produce significant infrared radiation.
d. Heat sink – any thermally conductive element designed to transfer heat from a heat
source (the LED) to the ambient environment. Heat sinks with fins are common and work
by creating a large surface area.
3.2.5 Thermal Resistance :
The flow of heat from an LED chip to the ambient environment can be modelled as a
series of thermal resistances between the chip (at Tj) and the ambient environment (Ta). The sum
of these resistances is the total thermal resistance for the system. The lower the thermal
resistance, the more effective design will be in conducting heat away from the LED chip
junction. For the entire path this is Rj-a and means the thermal resistance from junction to
ambient. Including smaller individual steps along the way gives the general equation for the
thermal resistance of the system:
Rj-a = Rj-c + Rc-hs + Rhs-a
Rj-c = resistance from LED junction to LED case
Rc-hs = resistance from LED case to heat sink
Rhs-a = resistance from heat sink to ambient

13. 13
3.3 SinkPAD Takes Thermal Substrate PCB to the Next Level:
Thermal substrate PCB is an innovative way through which manufacturers can use to
conduct heat away from their products. With the changes in technology, many products while
convenient suffer from heat generation. The resulting high temperatures can cause problems
with efficiency and reliability of products. Products fail to work as they should and it could
affect the reputation of a brand. The products also will not last long. SinkPAD focuses on
providing solutions that will help manufacturers deal with these problems efficiently. The
company spokesperson in a press address points out to the fact that although the technology
initially worked for LED applications, it is easily adapted for other uses as well. Manufacturers
dealing with overheating in their products can utilize the same concept and find a speedy
solution.
Fig.3.5 Sinkpad Showing Practical Example Of Direct Heat Transfer Path
The company assures that its thermally conductive pcb will see to the fast conduction
of this heat with increased efficiency. The heating of LED products reduces their efficiency,
reliability and reduces their lifespan. The company solutions provide an effective thermal
management process as the PCB components come prepped to reduce thermal resistance.
Manufacturers can get custom solutions that will work for just about any design regardless of
its size.
The products thermal conductivity substrate guarantees that no matter the application,
the heat generated will be easy to conduct away from the components. This increases the

14. 14
ability of the product to work as it should. If it is for lighting, the bulbs will be brighter and the
energy consumed will be less. This is good for saving costs as well as for the environment. The
technology helps in the provision on green energy.
Fig.3.6 Application Diagram Of Sinkpad PCB
It has its headquarters in the United States and a presence in Asia. It utilizes an
advanced thermally superior pcb technology that has a high reduction of LED junction heat. It
also deals with conventional MCPCB and FR4 printed circuit boards. Its SinkPAD technology
takes the conventional boards a notch higher with increased cooling and efficiency functions. It
provides solutions designed to the needs of the clients while saving costs as well as increasing
environmental protection. It guarantees its clients reliable and cost effective solutions that will
address just about any product heating challenges they may be facing.

15. 15
CAPTER 4
WORKING PRINCIPLE
4.1 SinkPAD Technology:
To understand how SinkPADTM
technology works let's first review the primary thermal
path found in LED applications. In a LED the heat originates at the chip (die) in the same way
that in a normal light bulb heat originates at the filament. The key difference is that in the case of
a light bulb the heat is radiated into the atmosphere and in the case of a LED heat must be
conducted through a series of mediums before it reaches the atmosphere. A high rate of thermal
conduction means cooler running LEDs while a low rate means very hot and potentially self-
destructive LEDs. If all substances had the same and low thermal resistance then it would not
matter how many mediums heat would have to be conducted through before it reached the
atmosphere. Since this is not the case, an ideal situation is one in which any substance with a low
thermal conductivity & a high thermal resistance is removed from the conduction thermal path.
These low thermal conduction/high thermal resistance substances slow the transfer of heat and
therefore increase junction temperature.
Fig.4.1 Constructional Dig. Of Sinkpad PCB And MCPCB
Typically conventional MCPCBs are commonly used to dissipate heat from a LED to a
heat sink. MCPCB uses a thermally conductive dielectric layer to bond circuit layer with base
metal (Aluminum or Copper). The key to thermal performance of MCPCB lies in its dielectric

16. 16
layer. Even though thermally conductive dielectric has higher thermal performance compared to
standard dielectric material it is still a weakest link in the conduction thermal path in the
MCPCB. SinkPADTM
PCB approach overcomes this limitation and eliminates use of a dielectric
material completely from a conduction thermal path. SinkPADTM
Technology provides “Direct
Thermal Path”, lowering LED junction temperature.
Fig.4.2 Heat Transfer Capability Of SINKPAD PCB Over MCPCB
4.2 Mounting & Cooling :
Use of this assembly requires careful attention to mounting and cooling to ensure that the
junction temperature of the LED is kept well below the maximum rating as specified in the LED
documentation published by Philips Lumileds. For optimal cooling, we recommend that the
assembly be mounted to a suitable finned heat sink (aluminum or copper) that is exposed to open
air. The assembly can be mounted to the heat sink in one of three ways:
1. through pressure sensitive, thermally conductive tape
2. by a thermally conductive adhesive
The bottom of the LED assembly is electrically neutral, so it is not necessary to electrically
isolate the base from the cooling surface. Once mounted, you need to confirm that the assembly
is being adequately cooled by testing the temperature of the LED as described in the Measuring
LED Junction Temperature section of this document.

17. 17
Fig.4.3 Bottom View Of Base Sinkpad
4.2.1 LED Mounting Using Pressure Sensitive Thermal Tape:
Pressure sensitive thermal tape such as our pre-cut Bond-Ply© 100 tape makes it easy to
fasten the base directly to a heat sink without the need for screws, clip mounts, or fasteners.
However in order to ensure a sound thermal bond, it is very important that the tape be used
correctly. This includes:
 Ensuring that all mating surfaces are clean, totally flat, and free of voids
 Sizing and positioning the tape so that all mating surfaces are covered
 Applying minimum of 10 PSI of even pressure between the LED and heat sink for at least
30 seconds
If pressure sensitive thermal tape is used correctly, there is no need to use any additional
mechanical fasteners.
4.2.2 LED Mounting Using Thermally Conductive Adhesive :
Thermally conductive adhesive such as Arctic Silver™ Thermal Adhesive requires a bit
more effort to use than thermal tape, but offers a permanent bond, wider operating temperature
range, and higher reliability, especially in environments where the assembly will be subjected to
mechanical shock and vibration. Like our thermal tape, we include a thermal press with every
order of Arctic Silver Thermal Adhesive to make it easier to create a sound bond.

18. 18
To create a thermally efficient and reliable bond:
 Ensure that all mating surfaces are clean and free of any grease or oil
 Use just enough epoxy to create as thin a bond line as possible
 Apply as much pressure as possible between the LED and heat sink for at least 30
seconds, and then maintain pressure using a clamp or weight until the epoxy has set
 Like our thermal tape, we include a thermal press with every order of Arctic Silver
Thermal Adhesive to make it easier to create a sound bond.
4.2.3 LED Mounting Using Mechanical Fasteners :
While the SP-02 includes three slots that can be used to fasten the LED assembly to a
heat sink using screws, we generally do not recommend this fastening method. As the LED is
directly soldered to the aluminum base, it is very easy to weaken or fracture the solder joint if the
screws are unevenly or over tightened. If your specific application requires that you fasten the
LED using screws, take extra care to ensure that the screws are carefully and evenly tightened,
and that you only use just enough thermal grease to fill any small voids.
4.2.4 SinkPAD-II™ 7 Rebel LED 40mm Round Assembly:
Fig.4.4 LED 40mm Round Assembly

19. 19
4.2.5 Series Operation :
To power all of the LEDs simultaneously (series operation), apply 6 solder dots to the
series configuration pads J1 to J6 and connect a suitable current regulating driver to the + and -
pads as shown in Image 3.
Fig.4.5 Series Operation
4.2.6 Parallel (Single) Operation:
To power and control each LED separately, simply connect a suitable current regulating
driver to each pad as shown in Image 4.
Fig.4.6 Parallel (Single) Operation

20. 20
4.3 Measuring LED Junction Temperature :
The junction temperature of the LED must be tested to ensure that it is being adequately
cooled. To make testing easy, the SP-02 assembly includes a temperature test point that can be
used to determine the LED junction temperature using the following procedure. For more details,
refer to the Thermal Model on page 10 of this document.
 Digital Multimeter
 Temperature measurement meter
 Thermocouple or thermistor with Kapton tape and/or thermal adhesive epoxy
1. Enter the LED Typical Thermal Resistance Junction to Thermal Pad (°C/W) RθJ-C value
from the Rebel LED datasheet into box B in the formula on page 9 of this document.
2. Ideally, the temperature should be tested with the LED assembly mounted in the location
where it will be operated.
4.3.1Test Procedure:
1. Enter the LED Typical Thermal Resistance Junction to Thermal Pad (°C/W) RθJ-C value
from the Rebel LED datasheet into box B in the formula on page 9 of this document.
2. Ideally, the temperature should be tested with the LED assembly mounted in the location
where it will be operated.
Fig.4.7 Test Procedure Of Hot LED

21. 21
3. .If the LED assembly is easily accessible, you can use a hand held temperature probe
such as our TP-01 Thermistor Tipped Probe to determine the LED junction temperature.
To measure the test point temperature with a hand held probe.
4. After the temperature measurement has stabilized, note the test point temperature.
Fig.4.8 Measure The Voltage Across The LED
5. Measure the forward voltage of the LED while at the stabilized temperature (Image 9)
and note it in box C.
6. Enter the current, which you are using to power the LED, in box D.
Fig.4.9 Measure The Voltage Across The LED
7. Evaluate the completed formula to determine the junction temperature of the LED.

22. 22
8. If you are powering all of the LEDs in series and the assembly is mounted to the center of
a symmetrically shaped heat sink in open air, then it is typically only necessary to test a
single LED to determine the junction temperature of all the LEDs. If the assembly’s
location will be difficult to reach, then you will need to attach a thermocouple or
thermistor to the assembly using Kapton tape or Arctic Silver™ Thermal Adhesive epoxy
so that the tip of the sensor is in direct contact with the temperature measurement point as
shown in Images 5 & 6. Be sure to allow the adhesive to fully cure before testing.
4.4 Thermal Model:
Image 10 is a cross-section of a typical SinkPAD-II™ LED assembly that illustrates how the
LED is attached to the SinkPAD-II™ base and shows the thermal paths between the LED
junction, temperature test point and bottom of the LED assembly.
 RθJ-C is the thermal resistance from the LED junction (Tj ) to the LED thermal pad
 RθC-S is the thermal resistance from the LED thermal pad to the temperature test point
(Ts )
 RθC-B is the thermal resistance from the LED thermal pad to the bottom of the
SinkPAD-II™ assembly .
Fig.4.10 Thermal Model Of Sinkpad PCB.

23. 23
4.5 Design Rules For Sinkpad Pcb :
If you are using Aluminum PCB now; “Thermal Pad / Bond Pad” From Current Design Will
Become “SinkPADTM”
1. If you are starting a brand new design; Consider Adding “SinkPADTM” Under Each
LED Component
2. Keep “SinkPADTM” Features On a Separate Gerber Layer (in PCB data)
3. “SinkPADTM” Size - smallest dimension must be minimum equal to the base metal
thickness
4. “SinkPADTM” Shape: Any Round is preferred, also it is the most cost effective shape
5. “SinkPADTM” Locations: minimum gap between two adjacent SinkPAD must be 0.060”
(1.52mm)
6. Specify Base Material: Type and Thickness (i.e. only base thickness) Standard
thicknesses 0.040” (1.0mm) & 0.062” (1.60mm) Aluminum/ Copper is available upon
request
7. Specify Dielectric Material: Type and minimum thickness, Typical high Tg FR4
8. Surface Finish Availability: HASL, Lead Free HASL, ENIG, OSP over all exposed
copper including SinkPAD pads
4.6 SinkPADTM Product Family:
SinkPAD P/N Base Metal Base Metal thickness
SP-A530 Aluminum 5052 ~0.032” (~0.80mm)
SP-A540* Aluminum 5052 ~0.040” (~1.0mm)
SP-A560* Aluminum 5052 ~0.063” (~1.60mm)
SP-A630 Aluminum 6061 ~0.032” (~0.80mm)
SP-A640 Aluminum 6061 ~0.040” (~1.0mm)
SP-A660 Aluminum 6061 ~0.059” (~1.50mm)
SP-C40 Copper ~0.040” (~1.0mm)
SP-C60 Copper ~0.059” (~1.50mm)
Table No.4.1 SinkPADTM Product Family

24. 24
CHAPTER 5
ADVANTAGES & DISADVANTAGES
5.1 ADVANTAGE:
 Maximum LED life
 Maximum lumens output
 Improved color rendering and stability
 Reduced cooling requirements means a smaller heat sink
 Create more densely packed LED designs
 Same light output with fewer LEDs means reduced cost
 Direct Thermal Path technology for ultimate cooling efficiency.
 Extremely low thermal resistance of 0.4 °C/W from the LED thermal pad to the
bottom of the aluminum base.
 Reduced LED junction temperature
 Can be mounted with thermal tape, epoxy or mechanical fasteners
5.2 DISADVANTAGE:
 The SinkPAD features second-generation technology that minimizes thermal
resistance by eliminating the dielectric layer so that the LED thermal pad is
soldered directly to the aluminum base. This ensures the lowest possible LED
junction temperature, resulting in increased LED life, lumens output and overall
reliability, but this process with increasing complexity than MCPCB .

25. 25
CHAPTER 6
CONCLUSION
6.1 INTRODUCTION:
The new Cree copper MCPCB available from FT have no substrate in the center solder
conduction pad. What you get is a direct electrical and thermal path from the LED to the
MCPCB. I know as I tore one apart which sold me on them. Copper 16mm XML Sinkpads on
the other hand have a knotted center section that in pressed in to accomplish the same task. I
haven't tried a 20mm yet but the 10mm does have a direct path as the Cree. I personally don't
think the pressed in piece on the 16mm Sinkpads is an issue although it might raise concerns to
those pushing 6 amps or more. I am perfectly happy with the quality of both the 16mm Cree and
16mm Sinkpad versions and plan on continuing to use them in my future builds.
An 'ordinary' MCPCB has a very thin fiberglass printed circuit board (PCB) laminated to
a metal substrate or core (MC). The center thermal contact of the led would get soldered to a
copper pad in the center of the PCB. Then there's a layer of fiberglass board between that and the
core. That thin layer has poor thermal conductivity, and almost all the heat has to pass through it.
It's very thin though, so in 'normal' applications it's not a problem. These boards are most often
done in aluminum because it's cheaper, though copper ones are available (copper has about
double the thermal conductivity of aluminum). An improvement on this is to cut a hole in the
fiberglass where the thermal pad is, and fill the hole with solder. Now the LED thermal pad is
soldered directly to the core. Solder has a thermal conductivity many times that of fiberglass, so
this is a notable improvement. There's one more improvement that can be made. Copper has
thermal conductivity about 8 times better than solder (depending on the alloys). So filling the
hole with copper is even better. This is done by deforming the core in a press, so that the core
material protrudes into the hole. Since these improvements are only done for the highest
performance levels, AFAIK, they are only done with copper.

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6.2 CONCLUSION:
SinkPAD corporation’s new thermal management printed circuit boards are a complete
and effective solution to the challenges faced by the solid state lighting industry, specifically
those with high power LED PCB applications. SinkPAD technology will improve any LED
application, but it will be most effective in high power (HP) & high bright (HB) surface mount
LED systems, especially those that are currently not effective enough at dissipating heat to be
viable. SinkPAD enables direct thermal path between LED and surrounding atmosphere.
SinkPAD is cost competitive in almost all cases, but in applications with active cooling systems
that are able to switch to passive cooling systems because of SinkPAD it is more than just
competitive; it is in a league of its own. Any LED application that requires active cooling can
reduce its reliance on the increased costs and moving parts involved even if it cannot be
completely eliminated. This is always a good thing, and often times, as an indirect effect the size
of the devices in these applications can also be reduced because of smaller or now non-existent
active cooling systems making these devices cheaper to make and more desirable to the
consumer.
6.3 FUTURE SCOPE:
 In future this technology will be very use full for lightning system.
 This technology became a need of our todays life to minimize rate of power required for
high power LED.
 This device should be fitted in every appliances in future.
 SinkPAD technology will improve any LED application.

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REFERENCES
1. http://en.wikipedia.org/wiki/sinnkpad technology
2. http://www.wikipedia.com
3. http://Sinkpad technologies.in
4. http://www.sinkpad.com
5. leds@halldata.com
6. http://www.theledshow.com/
7. http://www.strategiesinlight.com/
8. http://http//www.ledsmagazine.com/articles/2014/10/sinkpad-announces-thermally-
enhanced-linear-pcbs-at-the-led-show.html?cmpid=EnlLEDsOctober12014
9. http://www.lightshowwest.com/
10. http://www.google.com/

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