Directly Electroplated Metallization on Through Glass Via (TGV) Using Silver Nanowires Conductive Composite as Seed Layer

Glass interposer has attracted ever-increasing attention in 2.5D/3D advanced packaging field due to its excellent mechanical performance, thermal stability, easy manufacturing process and low cost. However, the poor adhesion between the glass surface and the deposited metal layer is a severe issue resulting from the smoothness of the glass surface, which limits its widespread applications. Herein, a novel method for realizing the direct copper electroplating on TGV is presented on the basis of a silver nanowire (AgNW) conductive composite. A pre-coat containing resin is firstly applied to the glass substrate as an adhesion layer. The glass substrate, on the other hand, requires only a simple cleaning process. The AgNW is then coated on the resin layer to form the conductive seed layer. Finally, the metallization of the TGV surface is rapidly achieved by direct copper electroplating. For TGVs with a diameter of 100 μm and a thickness of 500 μm, the surface morphology characterization indicates AgNW conductive composite is successfully coated on the TGV surface with a sheet resistance of approx. 39 Ω sq
^-1
, leading to rapid activation of the copper electroplating. The metallographic microscopy proves the asplated copper exhibits excellent coverage and plating uniformity across the TGV at 2 A/dm
²
for 40 min. To further evaluate the practical performance of the as-plated copper on glass, the adhesion of the deposited copper is conducted by tape-test technique under ASTM D3359-02. The results show the copper layer has strong adhesion to the glass. Our work provides an efficacious method to directly achieve the metallization of TGV with the advantages of high metal adhesion, simple and cost-effective process. Therefore, this approach has prominent potential for application in 2.5D/3D advanced packaging.