An Investigation Into Ball Grid Array Inspection Techniques

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Oesa STM-26I Figure 11. X-ray laminography focal planes for BGA inspection. CaITier slice Ball slice Pad slice Pad down slice - carrier slice, used to determinevoiding,bridging, insufficient,non-wetting,solder balls, alignment; - ball centre slice, used to determine voiding, missing ball, bridging, alignment; - pad slice, used to determine voiding, bridging, insufficient, non-wetting, solder balls, alignment; - pad down slice, allows for additional accuracy in detecting insufficients and opens. Once a stable production process has been established, the ball centre and pad slices are sufficient to determine most defects. The 50X is a floor standing real-time X-ray laminography system, with a footprint of 2.6 X 2.6 m.. Movementof the sample is automated with each image having a field of view of approximately 25 x 25 mm. The system has a typical selling price of €390 000. The images shown in this report are digitised images saved direct to media which have been mirrored and rotated to align with the images from other machines. 4.5. Equipment evaluation The four test samples were inspected by each of the machines. 14
5. Results This section is structured around an analysis of each sample in turn. Hence there is a comparison of defects on that sample between the various X-ray techniques, and a comparison with the optical micrographs. The optical micrographs are referred to as Reichert, the microscope used. 5.1 Results for Sample 1 Sample I contains partially retlowed solder joints. Figure Machine used Defects 12 13 14 15 16 17 18 19 20 21 22 Glenbrook Glenbrook Nicolet X-tekperpend. X-tekangled HP Four Pi 50x Reichert Reichert Reichert Reichert Reichert Partially reflowed solder joints Partially reflowed solder joints Partially reflowed solder joints Partially reflowed solder joints Partially reflowed solder joints Partially reflowed solder joints Non-reflow of solder paste Partial reflow of solder paste Complete reflow of solder paste Incomplete melting of ball Non-reflow of solder paste 15 Ball Grid Array Inspection Techniques Figure Summary I.
Page 1 and 2: An Investigation Into Ball Grid Arr
Page 3: Abstract An evaluation of four diff
Page 7 and 8: 1 Introduction X-ray techniques hav
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Page 13 and 14: 2.3 BGA PCB Image Summary of defect
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Page 17 and 18: 4. Equipment Evaluated Four machine
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Page 63: ~esa STM-261 Editor: Copyright: Pub

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