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首页> 外文期刊>IEEE transactions on electronics packaging manufacturing >Rework techniques process evaluation for chip scale packages
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Rework techniques process evaluation for chip scale packages

机译：芯片级封装的返工技术工艺评估

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摘要

The packaging formats, chip scale package (CSP) and ball grid array (BGA) have allowed significant reductions in component size compared to conventional surface mount devices (SMD) such as quad flat packs (QFP). However, the position of the solder joints formed (underneath the chip) after reflow means that visual inspection is impossible. For the defective chip, the only realistic method of rework is to remove and replace it. Component removal can be easily achieved, however replacement may be more complex. Difficulties in the procedure may arise from loss of terminations during the removal process, and high component population densities on printed circuit boards (PCB) may also inhibit access to the component pad site. The typical rework process consists of a number of steps including; component removal, PCB pad clean-up, flux or solder paste application, component placement and reflow. In this paper, we evaluate the pad clean up stage of the CSP rework process, including the design and analysis of a variety of solder paste or flux deposition techniques. Two PCB pad-cleaning methods have been compared and conclusions drawn from the resultant pad finish. Four deposition techniques have been assessed; these include mini-stencil, dip transfer, on- and off-contact stamping. Mini-stencil is the traditional method used in the electronics manufacturing industry for the deposition of solder paste onto reworked component sites. The remaining deposition techniques have been developed in order to overcome access restrictions that might exist on densely populated PCB's.
机译：与传统的表面贴装设备（SMD）（例如四方扁平包装（QFP））相比，封装格式，芯片级封装（CSP）和球栅阵列（BGA）大大减小了组件尺寸。但是，在回流焊之后（在芯片下方）形成的焊点位置意味着无法进行目视检查。对于有缺陷的芯片，返修的唯一现实方法是卸下并更换。可以轻松实现组件拆卸，但是更换可能更复杂。该过程中的困难可能是由于在移除过程中端子的丢失而引起的，印刷电路板（PCB）上的高组件密度也可能会阻止进入组件焊盘位置。典型的返工过程包括多个步骤，其中包括：组件移除，PCB焊盘清理，助焊剂或焊膏施加，组件放置和回流。在本文中，我们评估了CSP返工过程中的焊盘清理阶段，包括各种焊膏或助焊剂沉积技术的设计和分析。比较了两种PCB焊盘清洁方法，并从得到的焊盘抛光中得出了结论。已经评估了四种沉积技术。这些包括小型模板，浸入转移，接触式和脱接触式冲压。迷你模板是电子制造行业中用于将焊膏沉积到返工零件位置上的传统方法。为了克服可能在人口密集的PCB上存在的访问限制，已经开发了其余的沉积技术。

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