Large-format display fanless cooling — temperature spread halved
Redesigning the natural convection path and spreader orientation cut on-screen temperature spread from 6.8°C to 3.1°C, at zero added part cost.
- Challenge
- Localized hot region raising luminance uniformity and long-term reliability concerns. No fan permitted.
- Approach
- Opened a chimney flow path for natural convection and aligned anisotropic spreader orientation
- Result
- On-screen spread 6.8°C → 3.1°C, peak local temperature down 4.2°C
- Duration
- 9 weeks
Situation
On a large-format display that had to run fanless, a hot region developed toward the upper center of the panel. Absolute temperatures were within component ratings, but the 6.8°C spread across regions raised concerns about luminance uniformity over product life.
The constraints were unambiguous: no fan, no added thickness, no added part cost.
In natural convection, the flow path is everything
Unlike forced convection, natural convection has only buoyancy driving it. Performance is therefore governed by one question: can hot air actually get out at the top?
Simulation of the existing design showed rising air stalling inside the rear cover. There was a top opening, but a board bracket and a cable harness sat directly in front of it. Stagnant hot air was recirculating and re-heating the upper panel.
Changes
Three changes, none of which added cost:
- Opened a chimney path — revised the bracket geometry and rerouted the harness to clear the rising flow. The lower intake opening was repositioned but not enlarged.
- Aligned the anisotropic spreader — the sheet had been applied without regard to orientation. We aligned its high-conductivity axis with the direction spreading was actually needed. Same sheet, same area, different orientation.
- Relocated two hot components — moved them lower on the board so they sat upstream rather than downstream of the rising flow.
Outcome
- On-screen temperature spread 6.8°C → 3.1°C
- Peak local temperature down 4.2°C
- Zero added part cost — achieved entirely through geometry and placement
On a fanless product, check the flow path before adding thermal parts. What actually moved the heat here was not a new component but a few millimeters of space cleared so air could pass.
Figures published with customer consent.