Abstract:
The present invention relates to a method of placing solder balls (400) on a substrate (500) containing a plurality of semiconductor devices having input/output terminals (510) using a ball placement stencil (100) and to a corresponding ball placement stencil (100), the method comprising: - providing a substrate (500); - providing a plurality of balls (400) comprising solder; - providing a ball placement stencil (100) having an upper side (110) and a lower side (120), the ball placement stencil (100) comprising a plurality of apertures (105) for receiving the balls (400) and positioning the balls (400) on the substrate (500), and having attached thereto a plurality of discrete spacing means (200) (e.g. pillars) on the lower side (120); - positioning the ball placement stencil (100) adjacent the substrate (500) so that the ball placement stencil (100) is spaced from the substrate (500) by the spacing means (200); and - depositing the balls (400) onto the substrate (500) via the apertures (105) of the stencil (100), wherein the apertures (105) reduce in width from the upper side (110) towards the lower side (120). The reverse taper of the ball placement stencil (100) provides an upper opening (115) that readily accepts a solder ball (400), whilst providing a lower opening (125) that allows accurate positioning of the solder balls (400) on the substrate (500). The discrete spacing means (200) are arranged on the lower side (120) of the ball placement stencil (100) such that there is a clearance (210) between the edge of the discrete spacing means (200) and the lower opening (125) of each aperture (105). The cleareance (210) allows the discrete spacing means (200) to be located away from flux deposit (300) helping to retain the solder balls (400) in position on the substrate (500), thereby reducing the risk that flux (300) would adhere to the ball placement assembly and increase the need for intensive cleaning. Moreover, a plurality of markers may be located on the lower (120) and/or upper side (110) of the ball placement stencil (100) for alignment of the stencil (100) while positioning it on the substrate (500).
Abstract:
The present invention relates to a method of placing solder balls on a substrate, the method comprising: providing a substrate; providing a plurality of balls comprising solder; providing a ball placement stencil having an upper side and a lower side, the ball placement stencil comprising a plurality of apertures for receiving the balls and positioning the balls on the substrate, and having attached thereto a plurality of discrete spacing means on the lower side; positioning the ball placement stencil adjacent the substrate so that the ball placement stencil is spaced from the substrate by the spacing means; and depositing the balls onto the substrate via the apertures of the stencil, wherein the apertures reduce in width from the upper side towards the lower side.
Abstract:
Pillars (300, 306, 502) having a directed compliance geometry are arranged to couple a semiconductor die (400, 500) to a substrate. The direction of maximum compliance of each pillar (300, 306, 502) may be aligned with the direction of maximum stress caused by unequal thermal expansion and contraction of the semiconductor die (400, 500) and the substrate. Pillars (300, 306, 502) may be designed and constructed with various shapes having particular compliance characteristics and particular directions (302, 304, 308, 310, 504) of maximum compliance. The shape and orientation of the pillars (300, 306, 502) may be selected as a function of their location on a die (400, 500) to accommodate the direction and magnitude of stress at their location. Pillars (610) may also be fabricated with particular shapes by patterning a material (604) such as a passivation material on a pad on a die (600) to increase the surface area upon which the pillar (610) is plated or deposited.
Abstract:
Electromigration in microbump connections causes voids in the microbumps, which reduces the lifetime of an integrated circuit containing the microbump. Electromigration lifetime may be increased in microbumps by forming a copper or nickel shell around the solder. The copper shell (220, 408) of one microbump contacts the copper shell (234) of a second microbump to enclose the solder (222) of the microbump connection. The copper shell (220 & 234) allows higher current densities through the microbump. Thus, smaller microbumps may be manufactured on a smaller pitch without suffering failure from electromigration. Additionally, the copper shell reduces shorting or bridging between microbump connections on a substrate (202, 230). Increased connection densities between two dies (202,230)or between a die and a packaging substrate are therefore possible.
Abstract:
A substrate comprising a plurality of wet-able pads formed on a surface of the substrate; and a solder resist layer deposited on the surface of the substrate is obtained. At least the solder resist layer is formed with recessed regions defining volumes adjacent the wet- able pads. Molten solder is directly injected into the volumes adjacent the wet-able pads, such that the volumes adjacent the wet-able pads are filled with solder and the solder solidifies forming a plurality of solder structures adhered to the wet-able pads. The substrate and the solder are re-heated after the solidification, to re-flow the solder into generally spherical balls extending above the outer surface of the solder resist layer. In an alternative approach, solder injection and solidification are carried out in a nitrogen environment or a forming gas environment, and the reflow step may be omitted.
Abstract:
솔더 범프 전달 장치는 범프 패드들을 갖는 집적 회로 소자들이 형성된 웨이퍼를 지지하는 웨이퍼 척과, 상기 범프 패드들과 대응하는 표면 캐버티들을 갖고 상기 표면 캐버티들 내에 솔더 물질들이 채워진 템플릿을 지지하며, 상기 솔더 물질들과 상기 범프 패드들이 서로 마주하도록 배치되는 템플릿 척과, 상기 웨이퍼 척과 상기 템플릿 척 사이에서 이동 가능하도록 배치되며 상기 템플릿 상에 플럭스를 도포하기 위한 플럭스 도포 유닛과, 상기 템플릿 척과 연결되며, 상기 플럭스가 도포된 템플릿을 가열하여 상기 솔더 물질들을 구 형태를 갖는 솔더 범프들로 형성하기 위한 히터와, 상기 솔더 범프들을 상기 범프 패드들 상으로 전달하기 위하여 상기 웨이퍼 척과 상기 템플릿 척 사이에서 상대적인 수직 운동을 제공하는 구동부를 포함한다.