Issue link: https://iconnect007.uberflip.com/i/1547450
48 SMT007 MAGAZINE I NOVEMBER 2026 residue, and after component placement, there is no visible indication that a stencil was used during the rework process. Their main limitation is that they are generally intended for single use. Care is also required with very small apertures and fine-pitch arrays. When the stencil is removed, some solder paste can remain attached to the aperture walls and be lifted away from the PCB, reducing the deposited volume. This makes stencil thickness, aperture size, paste release, and removal technique increasingly impor- tant as pitch becomes finer. Stay-in-Place Stencils Stay-in-place stencils can provide one of the most consistent methods for controlling solder paste deposition during BGA rework. Because the stencil is held firmly against the PCB with a high-temper- ature adhesive and remains in place through the reflow cycle, it maintains alignment and helps keep the solder paste separated between adjacent pads. This can reduce the likelihood of bridging or shorts during placement and reflow. Another advantage is that the stencil does not need to be removed after printing, eliminating the risk of disturbing or lifting any paste during stencil removal. The tradeoff is that these stencils are single-use and remain on the assembly after rework. Once the BGA is installed, the stencil can still be visible beneath the edge of the component when viewed from the side. When cosmetic appear- ance or the absence of visible rework is important, a removable stencil may be preferred. Conclusion Stencil selection can have a significant effect on repeatability. Mini metal stencils offer durability and reuse when the site is accessible. Removable sten- cils are my preferred option for many standard BGA repairs because they sit flush to the board and leave no visible evidence after removal. Stay-in-place stencils provide excellent control of paste deposi- tion and alignment but remain visible beneath the finished component. The practical lesson is not that one stencil is best for every job. Start by deciding whether solder paste is needed at all. If it is, choose the stencil around the board geometry, pad size, pitch, and the needs of the specific rework. Good BGA rework depends on controlling solder volume, alignment, and heat; the right stencil simply makes those variables easier to manage. SMT007 Nash Bell is president of BEST, Inc. To read past columns, click here. K N O C K I N G D OW N T H E B O N E P I L E Figure 3: Removable adhesive-backed BGA stencil being peeled from the PCB after printing. Figure 4: Side view of a BGA installed over an orange stay-in-place stencil, which remains beneath the pack- age after reflow.