Pad-on-via assembly technique
    53.
    发明授权
    Pad-on-via assembly technique 失效
    Pad-on-via装配技术

    公开(公告)号:US06076726A

    公开(公告)日:2000-06-20

    申请号:US108482

    申请日:1998-07-01

    Abstract: Fine pitch area array packaging is achieved using a via-in-pad design within the area array attach portion of a printed circuit board (PCB). The limitation of the design is the wicking action, whereby solder applied to the capture pad contact surface is depleted by capillary action into the via hole when reflowed, causing insufficient solder to be present at the contact surface to effect reliable and repeatable electrical connections. In one implementation, an initial application of solder is applied to plug the via hole with a material having a higher final melting temperature than eutectic solder, thereby providing a stable plug. This plug is formed by the initial solder application that may be either a eutectic solder containing a third metal that forms intermetallic compounds, when reflowed, that elevate the liquidus temperature or a solder having a different formulation with an inherent higher melting temperature. An alternative implementation is to plate the via hole with a material, such as nickel, which prevents eutectic solder, applied to the via capture pad contact surface, from wetting the hole surface and being drawn away from the contact surface by capillary action. Thus, the solder, applied to the via capture pad and used to establish an electrical connection is not depleted.

    Abstract translation: 使用在印刷电路板(PCB)的区域阵列附着部分内的通孔焊盘设计实现细间距区域阵列封装。 设计的限制是芯吸作用,由此当回流时,施加到捕获垫接触表面的焊料被毛细管作用通入通孔中,导致在接触表面处存在不足的焊料以实现可靠和可重复的电连接。 在一个实施方案中,施加焊料的初始应用以用比共晶焊料更高的最终熔融温度的材料堵塞通孔,从而提供稳定的插塞。 该插头由初始焊料应用形成,其可以是包含形成金属间化合物的第三金属的共晶焊料,当回流时,提高液相线温度的焊料或具有固有的较高熔融温度的不同配方的焊料。 另一种实施方案是用诸如镍的材料对通孔进行平板化,其防止施加到通孔捕获垫接触表面的共晶焊料润湿孔表面并通过毛细管作用从接触表面拉出。 因此,施加到通孔捕获垫并用于建立电连接的焊料不会耗尽。

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