High-Aspect-Ratio Drilling

There are numerous apphcations such as high-aspect-ratio drilling that require an increased amount of vacuum pressure to remove debris sufficiently, and the equipment manufacturer can provide specific guidelines for special situations. Increasing the z-stroke distance between the pressure foot insert and the top of the drilled stack also assists in cooUng the drill bit. 

The test vehicle design has a significant impact on resnlts.The closer the circuit features, the more likely that CAF failures will occur. In addition, the other attributes of the test vehicle design can impact the fabrication variables that inflnence CAF—for example, the thickness of the PCB and drilled hole sizes can lead to high aspect ratios that can be more challenging to manufacture. As a result of these factors, there is not universal agreement on what constitutes a CAF-resistant material. This can vary by OEM and application. 

Sufficient vacuum flow is imperative when drilling high-aspect-ratio holes in tightly drilled grids. The vacuum system serves two main purposes ... 

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