Improvement of electrical insulating properties for defective metal/epoxy resin interface in power modules by micro-plasma jet

Abstract:

High-voltage power modules unavoidably deal with the basic issue of electric field contortion at triple-intersection point (Cu/protection substrate/preparing material) and unplanned presentation of unforeseen miniature metal imperfections on protection substrate, which harms electrical protecting properties and incites breakdown. In this review, an original exact surface treatment strategy in view of climatic tension miniature plasma stream (μ-APPJ) is proposed for reviving and further developing electrical protecting properties of blemished Cu/epoxy pitch (EP) substrate in power modules. Results show that a run of the mill μ-APPJ with a breadth of around 200 μm is created to unequivocally treat the miniature level metal deformity in Cu/EP interface, and a circular grouped Si-containing useful film (∼Si-O4) can be manufactured on EP substrate by improved Ar/Hexamethyldisiloxane (HMDSO)/μ-APPJ, which fundamentally upgrades the hydrophobicity of EP surface. Also, the plasma-helped film statement around μm-imperfection further develops interface electrical properties of inadequate Cu/EP tests, proved by higher flashover voltages and stifled halfway release. Further investigation in view of recreations uncovers that the kept normal film not just advances charge versatility and creepage distance on EP, yet in addition presents extra snare levels that catch electrons and hinder electric field around metal imperfections, in this way smothering fractional release disappointment and further developing electrical protecting properties.

Introduction:

High-voltage power modules are the center of different high-voltage and huge limit power transformation gear, which have turned into the essential gadgets that help the advancement of high-voltage DC power lattices [1], rapid railroads [2], aeronautics power supplies [3], and different fields. Be that as it may, confined by bundling protection, working voltage of force modules is a long way from arriving at as far as possible boundary of wide bandgap semiconductors (SiC or GaN) [4]. From one perspective, the triple-intersection point (Cu/protection substrate/preparing material) in power modules unavoidably causes field contortion, particularly the miniature level metal tip because of metal brazing or chip creasing further actuates fractional release (PD), and, surprisingly, electric breakdown [5]; then again, the unfortunate hydrophobicity of protection surface would be impacted by moistness and perilous gas, which starts the dendrite deformity and prompts protection corruption [6]. Subsequently, it is of extraordinary importance to treat the likely imperfections in power modules and work on the complete properties of triple-intersection interface, which gives a critical essential to creating cutting edge high-voltage power modules and ensuring their protected and solid activity.

Typically, streamlining of protection math is an immediate strategy to further develop the electric field circulation and electrical properties of triple-intersection interfaces[7], [8], [9]. Hourdequin et al. worked on direct fortified copper (DBC) substrates by adding grooves at the edge of the Cu layer, which essentially restrained PD force [8]. Yao et al. found that the bigger chamfer radii and channel distance in DBC substrates really changed the charge circulation, advancing the PD beginning voltage and electrical properties [9]. Notwithstanding, because of the prerequisites for scaling down and reconciliation of force modules, the improvement impact of bundling protection is restricted. Furthermore, nonlinear field-subordinate conductivity or permittivity protections [10], [11], [12], [13], [14], [15], for example, FGM-type SrTiO3/epoxy [10], SiC/alkyd gum [11], are additionally applied to homogenize nearby electric field conveyance and improve protecting properties, yet this material mass change is unreasonable somewhat for the neighborhood disappointment improvement, which not just deals with issues, for example, long handling cycle and wild field homogenization impact, yet in addition packs fine connection points or imperfections that might influence typical activity of force modules. Particularly, µm-level imperfections existing in power modules are likewise lethal variables that cause field twisting and protection breakdown, yet apparently, up until this point, hardly any reports have zeroed in on the exact treatment of deformities and execution improvement. In this manner, the ideal technique for electric field guideline and connection point property improvement is to develop a reasonable presentation upgraded film at the triple-intersection surface or connection point in bundling protection, to work on far reaching properties of bundling protection that meets the prerequisites for uniform field conveyance, good hydrophobicity, and upgraded electrical strength of force modules.

The quickly creating plasma innovation, as another sort of material surface treatment technique, could start physical and substance responses on material surface under gentle circumstances, for example, scratching [16], uniting [17], polymerization [18], and film statement [19], consequently controllably changing physical and synthetic properties of the material surface and manufacturing a designated useful film to accomplish material execution improvement. Lately, plasma adjustment innovation has likewise been applied in the exhibition improvement of force modules [20], [21], [22], [23]. Zhang et al. utilized Ar/CF4 inductively coupled plasma to clean the GaN surface in light of iota specific drawing for diminishing scratches and subsurface harm, which productively diminished the surface unpleasantness [20]; Jiang et al. accomplished the development of a thick protecting ceramic layer on SiCp/Al substrate in view of plasma electrolytic oxidation innovation, which worked on the electrical, warm and consumption obstruction qualities [21]. Moreover, taking into account the short protection distance (mm-level), little deformity size (µm-level) and unpredictable imperfection shape in power modules, further necessities are additionally advanced for the handling precision of plasma. Environmental tension plasma fly (APPJ), in which the release space and handling space are isolated and the plasma crest is controllable[24], [25], is for sure reasonable for little size and unpredictable substrate treatment, giving an extensive chance of exact change for triple-intersection focuses with µm-level defects[26], [27], [28], [29]. Accordingly, it is important to lay out an APPJ with µm-level plasma crest (μ-APPJ) and explore the impact of plasma treatment on flawed examples, to meet prerequisites of µm-deserts for exact treatment and electrical protecting execution improvement.

In this paper, a clever exact surface treatment technique in view of Ar/HMDSO/μ-APPJ is created for electrical protecting properties improvement of flawed metal/protection interface in power modules. Through enhancing the exploratory boundaries, the variety of surface hydrophobicity, PD power and flashover voltage of blemished examples are assessed, and the surface microstructure, atomic design and component sythesis are additionally dissected. Eventually, in view of quantum science reenactment, the multiphase responses among plasma and substrate are laid out and the system of execution improvement by plasma is uncovered.

Conclusion:

In this study, we proposed a novel treatment method based on plasma-assisted film deposition for inhibiting the defective Cu/EP interface in high-voltage power modules, and further investigated the multiphase interactions between Ar/HMDSO/μ-plasma and substrate surface. A rejuvenated Cu/EP interface with better hydrophobicity and higher flashover voltage can be constructed after plasma treatment, ensuring the safe and reliable operation of power modules. 

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