Direct Thermal Exchange Technology

Sometimes referred to as Pedestal technology

Daleba has developed a new patent-pending Direct Thermal Exchange Technology to aid modern thermal management issues of PCBs.

Electronics today are becoming more and more powerful with denser packaging and increased thermal management issues. The need to move heat away from components has never been greater. To achieve this the common method is to use conduction through the circuit to a heatsink or cold plate.

The efficiency of handling these thermal issues varies depending on the construction of the PCB and the Thermal Conductivity of the material used.

Ceramic substrate circuits are becoming more popular with their Thermal Conductivity values ranging from 24-180W/mK. The manufacturing constraints such as size and the cost of this new technology does not make it suitable for all applications. IMS (Insulated Metal Substrates) are a good solution for many. Initially introduced to combat rising junction temperatures of surface mount components on LEDs they consist of a thermally efficient electrically isolating dielectric layer between the copper tracks and an aluminium/copper base. Aluminium IMS tends to have a limit of between 8-10W/mK.

DTE – Direct Thermal Exchange Technology improves the thermal efficiency of IMS boards even further. The biggest thermal bottleneck of a metal core IMS is the dielectric, but with DTE the dielectric layer is bypassed by a plated, direct connection, through the dielectric to the base layer. These are sometimes called Pedestals. Thanks to this bypass, the heat can be transported with less thermal resistance, keeping the temperature of the component under control and extending its lifetime and operating performance. With their larger copper mass and efficiency, building pedestals will be more reliable compared to thermal vias ensuring a better spreading of the heat which allows for a better transfer to the heatsink.

The base layer for DTE has until now been copper which is heavy and expensive. Daleba offers DTE utilising a copper base but we have recently developed a patent-pending technology where the plated copper connection can bond to an aluminium base providing the traditional heatsinking materials of copper to aluminium. Our technology ensures the DTE (pedestal) does not separate from the aluminium base and has passed 1,000 cycles for thermal shock.

Pedestal Technology Introduction

Aluminium base DTE offers four distinct advantages over copper base DTE:

  • Lower weight
  • Lower cost
  • Similar thermal efficiency; aluminium circa 200 W/mK
  • Choice of advanced dielectrics
DTE Pedestal Technology - Etching Method For Copper Base
  • The 'Etch Method' for DTE Pedestal technology involves machining the Dielectric layer prior to bonding.
  • The base copper is etched away leaving only the pedestal required.
  • Once these two processes have been completed the two layers can be bonded together.
  • This process must allow for some registration tolerance between the machined dielectric and Pedestal size - generally leaving a minimum void of 0.1mm either side of the pedestal feature.
  • The resultant void can however leave the design open to potential Hi-Pot test failures - especially with humidity and/or thermal cycles.
  • Unlike DTE to an Aluminium base, FR4 dielectrics have to be used with a copper base.
Pedestal Technology Etch Method
DTE Pedestal Technology - Plating Method For Copper Base
  • The 'Plating Method' for Pedestal technology involves starting with the bonded substrate and achieves the pedestal by first machining away the dielectric to expose the metal base.
  • Copper is then plated up in these areas directly from the base to form the pedestal.
  • This is a more expensive method due to the higher cost of plating, and time required.
    However it does result in perfect registration between the dielectric and copper.
  • This neutralises the risk of the Hi-Pot test issues associated with voids.
  • Depending on thermal issues copper base may have to be thick and therefore heavy
  • Unlike DTE to an Aluminium base, FR4 dielectrics have to be used with copper base.
Pedestal Technology Plating Method
DTE Pedestal Technology - Plating Method For Aluminium Base
  • Daleba unique technology - Patent Pending
  • The majority of IMS materials used for Thermal Management consist of an Aluminium base metal as opposed to Copper.
  • DTE Pedestal technology was only previously possible using Copper as the base but Daleba have developed a way of plating a connection which is bonded to an aluminium base.
  • Thermal shock tested to 1000 cycles.
  • As a IMS aluminium substrate is used a wide range of exotic dielectrics are available.
  • Finished panel with aluminium much lighter than using a solid copper base
  • Aluminium base also offers substantial cost savings over solid copper.
  • This technology offers similar thermal performance to a copper base DTE board.
  • Can also be used for current, a micro via for electrical contact - copper layer to aluminium which allows the base layer to be a ground layer.
Pedestal Technology Aluminium Base
DTE Pedestal Technology - Capabilities
  Base Copper Weight (Thickness) Standard Special
Minimum Track Width 0.5oz (18um) 0.10 <0.10
1oz (35um) 0.10 <0.10
2oz (70um) 0.20 <0.20
3oz (105um) 0.25 <0.25
Minimum Track Gap 0.5oz (18um) 0.10 <0.10
1oz (35um) 0.15 <0.15
2oz (70um) 0.20 <0.20
3oz (105um) 0.25 <0.25
Hole Data Standard Special
Minimum Hole Size 1.20 N/A
Hole Tolerance - Drilled ±0.05 ±0.03
Hole Tolerance - Routed Holes ±0.10 +0 /-0.05
Minimum Hole to Edge 0.10 <0.10
Hole to Edge Tolerance ±0.15 ±0.10
Minimum Radial Clearance Pad (Annulus) 0.1 0.75
Min Pedestal SizeMin Pedestal Size
Max Pedestal SizeMax Pedestal Size
Pedestal GapPedestal Gap

Copper to Aluminium bond has passed the 1000 cycle test for thermal shock.

Number of Test Cycle (NCYCLE) 1000
Minimum Chamber Temperature (Tmin) -40°C
Maximum Chamber Temperature (Tmax) +125°C
Transfer Time (t2) between Chambers ≤10 S
Dwell Time (t) at low/high temp 15 minutes
DTE Pedestal Technology - Examples

Copper Base

Pedestal Example 1
Pedestal Example 2
Pedestal Example 3
Pedestal Example 4

Aluminium Base

Pedestal Technology Aluminium Base
DFE Pedestal Example
DFE Pedestal Example 2

These images show Daleba's unique DTE technology with a copper pedestal plated through the dielectric to produce a permanent bond to the aluminium base.

DFE Pedestal Example 3

Can also be used for current, a micro via for electrical contact - copper layer to aluminium which allows the base layer to be a ground layer. The above microsection was produced after 1000 cycle test for thermal shock.

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