Issue link: https://iconnect007.uberflip.com/i/1137649
64 SMT007 MAGAZINE I JULY 2019 Testing Methodology Two types of testing were performed: manu- facturability and reliability. Manufacturability: • Solder paste volume • Missing print • Hot slump, cold slump • Solder ball and two wetting tests • X-ray and visual inspection Reliability: • Accelerated temp cycle (0–100°C)— JEDEC 9701 • Four-point monotonic bend test— JEDEC 9702 Manufacturability: Solder Paste Volume We measured and analyzed the solder paste volume across six different aperture ratios ranging from 0.4–1.1. The apertures ranged from 8–22 mils (0.20–0.56 mm) using a 5-mil (0.13-mm) stencil. From Figure 4, Material D has somewhat less (although sufficient) volume consistently. All materials passed our internal company speci- fications. From Figure 5, Material D has somewhat less (although sufficient) volume consistently. All materials passed our internal specifications. From Figure 6, Material D has somewhat less (although sufficient) volume consistently. All materials passed our internal specifications. Figure 3: Cross-section of a BGA ball after 1,800 temperature cycles. Figure 5: Solder volume box plots for the 16-mil (0.40-mm) aperture with an area ratio of 0.8. Material A is the control. Figure 4: Solder volume box plots for the 22-mil (0.56-mm) aperture with an area ratio of 1.1. Material A is the control. Figure 6: Solder volume box plots for the 14-mil (0.36-mm) aperture with an area ratio of 0.7. Material A is the control.