Abstract
We present an interfacial strengthening technique for microsystem packaging, particularly at the interface of stiff and soft materials. Microsandglass shaped interlocks (MSIs) were first demonstrated at the interface of silicon and Nafion® and exhibited a strong interfacial strength of 1 MPa; moreover, nanowired micro-sandglass shaped interlocks (NW-MSIs) were employed to further enhance the interfacial strength, and a value of 3.4 MPa was achieved. Theoretical predictions indicated the enhancement factors include the gap shrinkage ratio, overhanging angle, contact area, and friction coefficient. The geometry of the MSIs is strongly dependent on the KOH etching time while the friction can be enhanced by the employment of nanowires on the sidewalls of MSIs. Based on the NW-MSIs, the highest interfacial strength obtained is 3.4-fold higher than that of MSIs without nanowires. © 2012 The Japan Society of Applied Physics.