Knocking Down the Bone Pile: Revamp Your Components with BGA Reballing
Global Sourcing Spotlight: Balancing Speed and Flexibility Without Sacrificing Control
SMT Perspectives & Prospects: Artificial Intelligence Part 6: Data Module 1
X-Ray Inspection of Lead and Lead-Free Solder Joints
July 31, 2017 | Glen Thomas, Ph.D., and Bill Cardoso, Ph.D., Creative Electron Inc.Estimated reading time: 13 minutes
where Emax is the maximum energy in the spectrum, which is 150keV for the X-ray machine used in this paper.
TIN-LEAD SOLDER VS. LEAD-FREE SOLDERS
There are a number of lead-free solder compounds in the market today. For examples in this analysis we used some of the solder compounds discussed in [5]. In particular, we compare eutectic tin-lead solder (63Sn/37Pb), tin-bismuth (42Sn/58Bi), and a variety of predominantly tin based solders, including tin-silver (98Sn/2Ag), tin-antimony (95Sn/5Sb), tin-indium-silver (77.2Sn/10In/2.8Ag), and tin-silver-copper (96.3Sn/3.2Ag/0.5Cu).
Solder compounds can be classified according to those he deems most likely lead-free alternatives, all of which have at least 95% Sn content[5]. In our analysis, we consider three of these (98Sn/2Ag, 95Sn/5Sb, and 96.3Sn/3.2Ag/0.5Cu). The others are provided for comparison purposes. Equation 4 must be discretized for evaluation. Using a Creative Electron’s proprietary emulation and simulation software, we computed the energy spectra and attenuation coefficients for 16 bands of 10keV width spanning 10keV to 160keV. Equation 4 in discrete form then becomes:
Using this data and accounting for filtration due to the X-ray source anode materials, we obtain values for all p(Ei ). The results are summarized in Figure 5. In Figure 6 we provide the stopping power (i.e., 1-I/I0) for five lead-free solder compounds and eutectic tin-lead solder at thicknesses of 2 mil, 5 mil, 10 mil, and 20 mil. The stopping power indicates the relative amount of X-rays that are attenuated in the material. For example, a stopping power of 0.75 means that three-quarters of the incident radiation is attenuated. Higher numbers consequently imply higher attenuation.
Figure 5: Energy spectrum of a TruView FUSION with a 150kV microfocus X-ray source.
Figure 6: Attenuation of lead-free solders and eutectic tin-lead solder. Note that the amount of attenuation at different material thicknesses is similar.
X-RAY IMAGE ANALYSIS
To validate the analysis presented in the previous session our Advanced Technology Group inspected a wide range of samples with both lead and lead-free solder composites. We compared eutectic tin-lead (63Sn/37Pb) and tin-bismuth (42Sn/58Bi) solders for their imaging profile using a TruView FUSION running at a maximum of 150kV. As expected, the X-ray images obtained from the samples using both types of solder did not present a notable difference. Please note that it is not the focus of this paper to compare the overall performance between lead and lead-free solders. Instead, the objective of this analysis is to validate that the X-ray machine settings work for both lead and lead-free solders.
Figure 7: Gullwing solder joints using both lead and leadfree solder paste. Note that the lead-free solder is slightly lighter (less dense) than the lead solder joint.
Page 3 of 5
Share on:
Testimonial
"We’re proud to call I-Connect007 a trusted partner. Their innovative approach and industry insight made our podcast collaboration a success by connecting us with the right audience and delivering real results."
Julia McCaffrey - NCAB GroupSuggested Items
Rehm Wins Mexico Technology Award for CondensoXLine with Formic Acid
10/17/2025 | Rehm Thermal SystemsModern electronics manufacturing requires technologies with high reliability. By using formic acid in convection, condensation, and contact soldering, Rehm Thermal Systems’ equipment ensures reliable, void-free solder joints — even when using flux-free solder pastes.
Indium Experts to Deliver Technical Presentations at SMTA International
10/14/2025 | Indium CorporationAs one of the leading materials providers to the power electronics assembly industry, Indium Corporation experts will share their technical insight on a wide range of innovative solder solutions at SMTA International (SMTAI), to be held October 19-23 in Rosemont, Illinois.
Knocking Down the Bone Pile: Revamp Your Components with BGA Reballing
10/14/2025 | Nash Bell -- Column: Knocking Down the Bone PileBall grid array (BGA) components evolved from pin grid array (PGA) devices, carrying over many of the same electrical benefits while introducing a more compact and efficient interconnect format. Instead of discrete leads, BGAs rely on solder balls on the underside of the package to connect to the PCB. In some advanced designs, solder balls are on both the PCB and the BGA package. In stacked configurations, such as package-on-package (PoP), these solder balls also interconnect multiple packages, enabling higher functionality in a smaller footprint.
Indium to Showcase High-Reliability Solder and Flux-Cored Wire Solutions at SMTA International
10/09/2025 | Indium CorporationAs one of the leading materials providers in the electronics industry, Indium Corporation® will feature its innovative, high-reliability solder and flux-cored wire products at SMTA International (SMTAI), to be held October 19-23 in Rosemont, Illinois.
‘Create your Connections’ – Rehm at productronica 2025 in Munich
10/08/2025 | Rehm Thermal SystemsThe electronics industry is undergoing dynamic transformation: smart production lines, sustainability, artificial intelligence, and sensor technologies dominate current discussions.