<p>During long-term storage, the pad plating of ceramic column grid array (CCGA) devices is susceptible to oxidation, leading to the formation of refractory oxides that are difficult to remove. This compromises the wettability of solder joints and undermines their long-term service reliability. To address this issue, this study introduces an innovative laser cleaning process as a pretreatment step for CCGA devices. The influence of laser power on cleaning efficacy was systematically evaluated. Results show that at an optimized power of 9 W, oxide content on the pad surface is markedly reduced, effectively alleviating non-wetting defects. Importantly, the laser treatment causes no significant alteration to the ceramic substrate or plating thickness, demonstrating its selectivity in removing oxides without damaging the underlying material. Mechanical testing confirms that the shear force of the resulting solder joints remains within the specified requirements. Furthermore, thermal cycling tests (−65°C to 150°C) were conducted to investigate interfacial evolution. A uniform and continuous intermetallic compound (IMC) layer was observed at the solder joint interface, with its total thickness (<i>δ</i>) following a power-law relationship with aging time (<i>t</i>), i.e., <i>δ</i> ∝ <i>t</i><sup>(1/2)</sup>. This behavior indicates that the interfacial growth is governed by a diffusion-controlled mechanism, reflecting stable and predictable evolution. In conclusion, laser cleaning offers an effective solution to non-wetting issues in CCGA assemblies and contributes significantly to ensuring their reliability in long-term service.</p>

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Laser Cleaning for Mitigating Non-Wetting in CCGA Solder Joints While Preserving Joint Reliability

  • Xujing Nan,
  • Zhipeng Mei,
  • Chang Su,
  • Zhaoying Yang,
  • Baocheng Wang,
  • Liang Qiao

摘要

During long-term storage, the pad plating of ceramic column grid array (CCGA) devices is susceptible to oxidation, leading to the formation of refractory oxides that are difficult to remove. This compromises the wettability of solder joints and undermines their long-term service reliability. To address this issue, this study introduces an innovative laser cleaning process as a pretreatment step for CCGA devices. The influence of laser power on cleaning efficacy was systematically evaluated. Results show that at an optimized power of 9 W, oxide content on the pad surface is markedly reduced, effectively alleviating non-wetting defects. Importantly, the laser treatment causes no significant alteration to the ceramic substrate or plating thickness, demonstrating its selectivity in removing oxides without damaging the underlying material. Mechanical testing confirms that the shear force of the resulting solder joints remains within the specified requirements. Furthermore, thermal cycling tests (−65°C to 150°C) were conducted to investigate interfacial evolution. A uniform and continuous intermetallic compound (IMC) layer was observed at the solder joint interface, with its total thickness (δ) following a power-law relationship with aging time (t), i.e., δ ∝ t(1/2). This behavior indicates that the interfacial growth is governed by a diffusion-controlled mechanism, reflecting stable and predictable evolution. In conclusion, laser cleaning offers an effective solution to non-wetting issues in CCGA assemblies and contributes significantly to ensuring their reliability in long-term service.