Thermal Design for High Current PCB-Mount Barrel Jacks

GlobTek Inc. 2019

The below information pertains to the following GlobTek parts:

  • JACK-L-PC-10A-RA(R)
  • JACK-C-PC-10A-RA(R)

GlobTek’s JACK-L-PC-10A-RA(R) and JACK-C-PC-10A-RA(R) jacks carry a 10A continuous current rating, allowing a high current connection to be made directly to the target PCB. The contacting interface in an electrical connection is never perfect, leading to an equivalent contact resistance at the junction of the male and female connectors.

Robust connectors, like GlobTek’s 10A PCB-mount jacks, have low values of contact resistance. Even so, at high operating currents, this resistance is not negligible and causes heating in the connector. Operating the connector at excessive temperatures can cause damage to the connector, the PCB, and poses a potential safety risk.

Therefore, it is important to assess whether additional measures are required to keep the jack at a safe operating temperature. The main contributing factors are:

  1. Ambient temperature
  2. Maximum continuous current

The most straight-forward approach is to provide heatsinking via additional PCB copper area near the connector. This increased surface area allows for better cooling via natural convection. The required copper area depends largely on the the application.

GlobTek produced a thermal evaluation board to test the effectiveness of PCB heatsinking in this application. (Image shown on next page.) Using the smallest PCB area (22.0 x 28.0mm on front and back sides), testing showed that it was possible to pass 10A through the connector, at 55°C, with no degradation to the connector during a 24 hour test. Under these conditions, the connector center pin temperature, reaches just over 130°C. Therefore, if using GlobTek’s jacks in a similar scenario, it is important to consider the maximum operating temperature of the PCB. Use of a 130°C minimum operating temperature rated board is required.

If using GlobTek’s PCB-mount barrel jacks with a higher ambient temperature, 85°C for example, the following solutions may be applied:

  1. Increased PCB copper area (especially on higher resistance center pin plane)
  2. Increased copper thickness
  3. Increased PCB operating temperature rating
GlobTek Thermal Evaluation Board for JACK-L-PC-10A-RA(R) and JACK-C-PC-10A-RA(R)
Above: GlobTek Thermal Evaluation Board for JACK-L-PC-10A-RA(R) and JACK-C-PC-10A-RA(R)
Copper thickness: 2oz (0.071mm)

Sample PCBs for customer thermal evaluation are available upon customer request to GlobTek, a small service charge may be applied.

Please note, the sample PCB has options for 3 different copper areas. The 22 x 28mm copper area evaluation board, has been tested under various conditions, see following page for thermal data. The largest board on the bottom, has approximately twice the copper area.

CONNECTOR TEMPERATURE MEASUREMENT SUMMARY

USED PSU P/N:
TR9KE9000CCP‐IM(R6B)
TR9KE9000LCP‐IM(R6B)
Connector's P/N:
JACK‐C‐PC‐10A‐RA(R) 2.1mm
JACK‐L‐PC‐10A‐RA(R) 2.5mm
Test condition A
CONNECTOR P/NAmbient TempLoadTotal HoursCENTER Pin_Highest temp readingSHELL_Highest temp reading
JACK‐C‐PC‐10A‐RA(R ) 2.1mm55°C10A22.86116.4°C88.9°C
JACK‐L‐PC‐10A‐RA(R ) 2.5mm55°C10A22.86132.8°C97.6°C
Test condition B
CONNECTOR P/NAmbient TempLoadTotal HoursCENTER Pin_Highest temp readingSHELL_Highest temp reading
JACK‐C‐PC‐10A‐RA(R ) 2.1mm85°C8A25.11156.54°C116.31°C
JACK‐L‐PC‐10A‐RA(R ) 2.5mm85°C8A25.11141.97°C115.88°C
Test condition C
CONNECTOR P/NAmbient TempLoadTotal HoursCENTER Pin_Highest temp readingSHELL_Highest temp reading
JACK‐C‐PC‐10A‐RA(R ) 2.1mm85°C10A21.45176.14°C128.89°C
JACK‐L‐PC‐10A‐RA(R ) 2.5mm85°C10A21.45177.46°C134.33°C

All testing done with thermal chamber with still air, and with 22x28mm copper area top and bottom side, 2 oz copper.

Tested by: EV

CONNECTOR EVALUATION BOARD AND TEST SET‐UP PHOTOS

GLOBTEK RECOMMENDED MOUNTING BOARD FOR THE CONNECTORS

Note, maximum hotspot temperature on the PCB will be approximately 10°C cooler than the hot spot on the center pin, due to thermal gradient along the pin length as it merges into the large copper plane area.

Suggested board operating temperature rating (please confirm in end application, with thermal probes)

Condition A—130°C or 140°C
Condition B—150°C or 160°C
Condition C—170°C or 180°C

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