Cu@Ag core-shell material not only has advantages of Cu and Ag elements but also inhibits Ag migration and Cu oxidation issues, showing potential in die attachments for power electronics. Currently, micro/nano sintering has been widely used for die attachments and inevitably forms residuals and voids due to solvents, leading to poor bonding strength and weak reliability. In this work, a high-temperature Cu@Ag solder preform was firstly fabricated by electromagnetic compaction (EMC) on Cu@Ag core-shell powder. Unlike conventional solder preforms, a void-free joint can be directly achieved with this Cu@Ag solder preform by simple thermal compression at low temperature and pressure without melting. Moreover, with the benefits of high-energy forming process, other vital properties of solder preforms, including electrical property, thermal stability, corrosion resistance and joint integrity, were also improved compared to conventional die attach materials. For instance, the corrosion potential of this Cu@Ag solder preform was −0.14 V, which indicates excellent corrosion resistance similar to pure Ag (−0.12 V). And no oxidation can be detected on this solder preform after storage in air for at least one year. These performance improvements were a result of enormous pressure generated instantaneously on Cu@Ag powder during EMC. The results showed that a flaw-free Cu@Ag solder preform with a high compactness of over 99 % can be successfully fabricated by appropriate compaction pressure of 13.4 MPa.

Cu @ Ag核壳材料不仅具有Cu和Ag元素的优势，而且还抑制了Ag迁移和Cu氧化问题，显示出在电力电子芯片连接中的潜力。当前，微/纳米烧结已被广泛地用于管芯附着，并且不可避免地由于溶剂而形成残留物和空隙，从而导致较差的粘结强度和较弱的可靠性。在这项工作中，首先通过电磁压紧（EMC）在Cu @ Ag核壳粉末上制备了高温Cu @ Ag焊料预制棒。与传统的焊料预成型件不同，该Cu @ Ag焊料预成型件可通过在低温和低压下简单地热压缩而不会熔化而直接实现无空隙连接。此外，借助高能成型工艺的好处，焊料预成型坯的其他重要性能，包括电性能，热稳定性，与传统的芯片连接材料相比，耐腐蚀性和接头完整性也得到了改善。例如，这种Cu @ Ag焊料预制棒的腐蚀电位为-0.14 V，这表明与纯Ag（-0.12 V）相似的优异的耐腐蚀性。在空气中存放至少一年后，在该焊料预成型坯上没有发现氧化。这些性能的提高是在EMC期间瞬间在Cu @ Ag粉末上产生巨大压力的结果。结果表明，通过适当的13.4 MPa压制压力，可以成功地制造出压实度超过99％的无缺陷Cu @ Ag焊料预制棒。这表明与纯银（-0.12 V）相似的优异耐腐蚀性。在空气中存放至少一年后，在该焊料预成型坯上没有发现氧化。这些性能的提高是在EMC期间瞬间在Cu @ Ag粉末上产生巨大压力的结果。结果表明，通过适当的13.4 MPa压制压力，可以成功地制造出压实度超过99％的无缺陷Cu @ Ag焊料预制棒。这表明与纯银（-0.12 V）相似的优异耐腐蚀性。在空气中存放至少一年后，在该焊料预成型坯上没有发现氧化。这些性能的提高是在EMC期间瞬间在Cu @ Ag粉末上产生巨大压力的结果。结果表明，通过适当的13.4 MPa压制压力，可以成功地制造出压实度超过99％的无缺陷Cu @ Ag焊料预制棒。