Issue link: https://iconnect007.uberflip.com/i/1161956
SEPTEMBER 2019 I SMT007 MAGAZINE 91 microns immersion gold on top. Thickness lev- els were not changed, so as not to be a vari- able (Figure 2). The EPIG film thickness used equals 0.375 microns palladium phosphorus with 0.025 microns immersion gold on top. Again, thick- ness was held to one level for testing duration (Figure 3). The solder flux used was composed of 25% ±0.5% colophony, 0.39% ±0.01% diethyl- ammonium chloride, and the balance isopro- pyl alcohol. The solder alloy employed was a SAC 305 alloy consisting of 3% silver, 0.5% copper and the balance tin. The solder tem- perature was set at 255°C. The contact time between the solder and sample measures wet- ting time and soldering final force. A production solder wetting balance was used to measure time to wet and solder force (Figure 4). A production XRF machine was used to measure plating thicknesses (Figure 5). Steam aging apparatus used was as outlined in IPC J-STD-002/003 as shown in Figure 6. The solderability evaluation procedure engaged was to first plate solder test coupons with ENIG and EPIG. Both of these plating processes utilized the exact same preparation Figure 4: Wetting balance used to test solderability. Figure 5: XRF used to measure plate thicknesses of the ENIG and EPIG test samples. Figure 6: Steam aging apparatus used to stress ENIG and EPIG solder wicking. Figure 2: Diagram of ENIG plate tested. Figure 3: Diagram of EPIG plate tested.