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Head-in-pillow X-ray Inspection
June 10, 2014 |Estimated reading time: 1 minute
Abstract
Manufacturing technology faces challenges with new packages/processes when confronting the need for high yields. Identifying product defects associated with the manufacturing process is a critical part of electronics manufacturing. In this project, we focus on how to use AXI to identify BGA head-in-pillow (HIP), which is challenging for AXI testing. Our goal is to help us understand the capabilities of current AXI machines.
For the study, we used two boards exhibiting HIP defects with four types of AXI machines located at four Flextronics sites, or at a vendor laboratory. The AXI machines used have different X-ray technologies: laminography and tomosynthesis. We collected three sets of data with AXI 1 machine (laminography), and AXI 4 machines (tomosynthesis); one set of data with AXI2 (tomosynthesis); and four sets data for AXI3 (tomosynthesis). We studied AXI measurement data with the different AXI algorithm threshold settings. The data indicated clearly that the Algorithm Threshold settings are very critical for detecting HIP, including open. The defective HIP pins are validated by using 2DX and CT scan.
The test data consist of defects escaped %, false call ppm and also gage R&R. The AXI images for HIP pins, false call pins and defects escaped pins are presented in the paper. The 2DX and CT images are provided for identifying HIP type (shape and size).
Introduction
More BGA and area array devices are appearing on PCBAs as product and functional complexity increases. Furthermore, to achieve good signal integrity, more I/Os are packed in smaller areas within the available real estate. It is very important to use AXI and other non-destructive techniques to identify BGA joint qualities and prevent escape. We did a study for BGA crack several years ago with AXI, time domain reflectometry (TDR), 2DX, and cross-section/SEM comparison; however, we didn’t have good detected results from AXI. During the study, we realized that 2D X-ray with tilting angle detector has the capabilities to identify BGA crack at 5 microns or higher. Recently more AXI machines using both laminography and tomosynthesis technologies have better capabilities to detect BGA defects; therefore we would like to develop the optimization algorithm and threshold settings to identify HIP on BGA for high-volume products. Read the full article here.Editor's Note: This article originally appeared in the May 2014 issue of SMT Magazine.