Beyond Design: The Fundamental Structure of Spectral Integrity
Elementary, Mr. Watson: High Power: When Physics Becomes Real
The Shaughnessy Report: Watt About Power Integrity?
Book Excerpt: The Printed Circuit Designer’s Guide to... Thermal Management with Insulated Metal Substrates, Chapter 2
October 10, 2023 | I-Connect007 Editorial TeamEstimated reading time: 1 minute
Chapter 2: Solder Cracks
Historically, engineering teams using some types of insulated metal substrates in high-performance LED applications have noted the formation of solder cracks after prolonged thermal cycles. Solder cracks, as the name suggests, are discontinuities in the solder joint, usually caused by excessive mechanical stress. This stress typically results from a mismatch between the coefficients of thermal expansion (CTE) of each of the joined components. Through repeated thermal cycling, the tendency of the joined parts to expand and contract at different rates eventually overcomes the solder’s ability to resist that differential displacement. A crack then forms in the solder. Crack formation like this can be aided by soldering defects such as poor wetting at either surface or inclusion of impurities within in the solder.
A solder crack impairs both the mechanical integrity of the joint and the electrical continuity. The mechanical weakness may not be detected, especially if there are several such connections and others are unaffected. The electrical discontinuity may be partial, manifested as increased ohmic resistance if the separated surfaces remain in contact, or may cause an intermittent open circuit. Each can cause defective functioning of the circuit or system.
Figure 2.1 shows possible root causes of such solder cracks. Although this list is not exhaustive, any combination of these effects can contribute towards conditions that cause solder cracks to occur.
As a designer and manufacturer of laminate, Ventec can directly influence multiple aspects relating to materials selection and use, including:
- Minimizing percentage of copper on circuit side
- Use Super HTE (High-Temperature Elongation) copper foil with lower tensile strength
- Lower Tg dielectric working in elastic deformation zone
- Lower CTE of aluminum baseplate (CTE is 19 ppm/K)
- Copper baseplate
- Choosing high-performing dielectric
In addition, the effect each crack or void in the solder joint has on the thermal path of the system must also be considered. A representative approximation is that a crack affecting 50% of the solder pad area will double the thermal impedance.
Share on:
Testimonial
"In a year when every marketing dollar mattered, I chose to keep I-Connect007 in our 2025 plan. Their commitment to high-quality, insightful content aligns with Koh Young’s values and helps readers navigate a changing industry. "
Brent Fischthal - Koh YoungSuggested 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.