X-ray inspection and Six-Sigma in analysis of LED thermal pad coverage

Dziurdzia

2018

SSMT

Self Cite

Purpose This paper aims to present the results of the influence of a manner of soldering light emitting diodes (LEDs) to the metal core printed circuit board on thermal parameters of the module LED containing these diodes. Design/methodology/approach Using the authors’ elaborated measuring method and the dedicated measurement set-up, transient thermal impedances of LED modules, mounted using different soldering processes and mounted to the heat-sink with different values of the moment of force, are measured. The obtained results of measurements are discussed. Findings It was shown experimentally that the manner of soldering could strongly influence efficiency of dissipation of heat generated in the module. The best thermal properties were obtained for soldering using vapour phase technology with vacuum and paste LFS-216LT. It was also proved that the moment of force used while mounting the considered modules on the heat-sink can result in a change of the value of thermal resistance of this module exceeding even 12 per cent. Research limitations/implications The investigations were performed for five LED modules operating at one, arbitrarily selected value of power dissipated in these modules mounted on the heat-sink of arbitrarily selected dimensions. Practical implications The obtained results of measurements could be usable for designers of mounting processes of power LED modules. Originality/value This paper presents the results of investigations of thermal properties of LED modules, in which different techniques of soldering are used. It was shown experimentally that the manner of soldering could strongly influence efficiency of dissipation of heat generated in the module. It was also proved that the moment of force used while mounting the considered modules on the heat-sink is important.

Section: Investigated Light Emitting Diode Modulesmentioning

confidence: 99%

“…Five batches of LEDs of 80 pcs each underwent the analysis. These considered LED modules are described in the papers by Dziurdzia and Mikołajek (2016) and Dziurdzia and Mikołajek (2017).…”

Section: Investigated Light Emitting Diode Modulesmentioning

confidence: 99%

The influence of a soldering manner on thermal properties of LED modules

Dziurdzia

2018

SSMT

Self Cite

“…The optical and thermal parameters strongly depend on the properties of the solder joints (Dziurdzia et al , 2019). It has also been proven that soldering the elements with a large thermal pad (LEDs) encourages other reliability problems (Dziurdzia and Mikołajek, 2017; Dziurdzia et al , 2018).…”

Section: Introductionmentioning

confidence: 99%

The influence of SACX0307-ZnO nanocomposite solder alloys on the optical and thermal properties of power LEDs

Skwarek

et al. 2022

SSMT

Purpose This paper aims to present the results of investigations that show the influence of ZnO composite soldering paste on the optical and thermal parameters of power light-emitting diodes (LEDs). Design/methodology/approach ZnO nanocomposite solder alloys were produced via the ball milling process from the solder paste Sn99Ag0.3Cu0.7 (SACX0307) and 1.0 wt% of ZnO nanoparticle reinforcements with different primary particle sizes (200 nm, 100 nm and 50 nm). Power LEDs were soldered onto a metal core printed circuit board. A self-designed LED test system was used to measure the thermal and optical characteristics of the LEDs. Findings The influence of the soldering paste on the thermal and optical parameters of LEDs was observed. In all solder alloys, ZnO ceramic reinforcement, at a level of 1 wt%, increased the thermal parameters of LEDs and decreased their luminous efficiency. Thermal resistance values were10% higher, and junction temperature change over ambient temperature was 20% higher for the samples soldered with composite solder pastes than the reference sample. At the same time, luminous efficiency dropped by 32%. Originality/value The results prove that ZnO ceramic reinforcement of solder paste influences the thermal properties of solder joints. As was proven, the quality of the solder joints influences the whole assembly.

“…It was shown that using soldering paste SACX0307-TiO 2 , it is possible to obtain visibly better thermal properties of soldering joints than using classical paste SACX0307. In their papers (Dziurdzia et al, 2018;Dziurdzia and Mikołajek, 2017), the influence of the parameters of the soldering process on the quality of the joints obtained was analyzed. The results of the investigations presented illustrate that the number of voids observed in the soldering joint depends on parameters that characterize the soldering process of BGA cases.…”

Section: Introductionmentioning

confidence: 99%

The influence of soldering process parameters on the optical and thermal properties of power LEDs

Skwarek

et al. 2020

SSMT

Purpose This paper aims to present the results of investigations that show the influence of soldering process parameters on the optical and thermal parameters of power LEDs. Design/methodology/approach The power LEDs were soldered onto metal core printed circuit board (MCPCB) substrates in different soldering ovens: batch and tunnel types, characterized by different thermal profiles. Three types of solder pastes based on Sn99Ag0.3Cu0.7 with the addition of TiO2 were used. The thermal and optical parameters of the diodes were measured using classical indirect electrical methods. The results of measurements obtained were compared and discussed. Findings It was shown that the type of oven and soldering thermal profile considerably influence the effectiveness of the removal of heat generated in the LEDs tested. This influence is characterized by thermal resistance changes. The differences between the values of this parameter can exceed 20%. This value also depends on the composition of the soldering paste. The differences between the diodes tested can exceed 15%. It was also shown that the luminous flux emitted by the diode depends on the soldering process used. Practical implications The results obtained could be useful for process design engineers for assembling power LEDs for MCPCBs and for designers of solid-state light sources. Originality/value This paper presents the results of investigations into the influence of the soldering profiles and soldering pastes used on the effectiveness of the removal of heat generated in power LEDs. It shows and discusses how the factors mentioned above influence the thermal resistance of the LEDs and optical parameters that characterize the light emitted.