Technical Library | 2023-11-27 18:19:40.0
This page introduces major causes and countermeasures of solder crack in MLCCs (Multilayer Ceramic Chip Capacitors). Major causes of solder cracks Solder cracks on MLCCs developed from severe usage conditions after going on the market and during manufacturing processes such as soldering. Applications and boards that specially require solder crack countermeasures Solder cracks occur mainly because of thermal fatigue due to thermal shock or temperature cycles or the use of lead-free solder, which is hard and fragile.
Technical Library | 2014-06-19 18:13:23.0
For high-density electronic packaging,the application of flip-chip solder joints has been well received in the microelectronics industry. High-lead(Pb) solders such as Sn5Pb95 are presently granted immunity from the RoHS requirements for their use in high-end flip-chip devices, especially in military applications. In flip-chip technology for consumer electronic products, organic substrates have replaced ceramic substrates due to the demand for less weight and low cost. However, the liquidus temperatures of high-Pb solders are over 300°C which would damage organic substrates during reflow because of the low glass transition temperature. To overcome this difficulty, the composite solder approach was developed...
Technical Library | 2019-08-15 13:31:52.0
Cracks in ceramic chip capacitors can be introduced at any process step during surface mount assembly. Thermal shock has become a "pat" answer for all of these cracks, but about 75 to 80% originate from other sources. These sources include pick and place machine centering jaws, vacuum pick up bit, board depanelization, unwarping boards after soldering, test fixtures, connector insulation, final assembly, as well as defective components. Each source has a unique signature in the type of crack that it develops so that each can be identified as the source of error.
Technical Library | 2008-10-23 15:36:58.0
As part of continuous process improvement at KEMET, most failure modes caused by the capacitor manufacturing process have been systematically eliminated. Today these capacitor manufacturing-related defects are now at a parts per billion (PPB) level. Pareto analysis of customer complaints indicates that the #1 failure mode is IR failure due to flex cracks.
Technical Library | 2022-09-25 20:18:33.0
Printed circuit board (PCB) bending and/or flexing is an unavoidable phenomenon that is known to exist and is easily encountered during electronic board assembly processes. PCB bending and/or flexing is the fundamental source of tensile stress induced on the electronic components on the board assembly. For more brittle components, like ceramic-based electronic components, micro-cracks can be induced, which can eventually lead to a fatal failure of the components. For this reason, many standards organizations throughout the world specify the methods under which electronic board assemblies must be tested to ensure their robustness, sometimes as a pre-condition to more rigorous environmental tests such as thermal cycling or thermal shock.
Technical Library | 2022-09-25 20:03:37.0
Cracking remains the major reason of failures in multilayer ceramic capacitors (MLCCs) used in space electronics. Due to a tight quality control of space-grade components, the probability that as manufactured capacitors have cracks is relatively low, and cracking is often occurs during assembly, handling and the following testing of the systems. Majority of capacitors with cracks are revealed during the integration and testing period, but although extremely rarely, defective parts remain undetected and result in failures during the mission. Manual soldering and rework that are often used during low volume production of circuit boards for space aggravate this situation. Although failures of MLCCs are often attributed to the post-manufacturing stresses, in many cases they are due to a combination of certain deviations in the manufacturing processes that result in hidden defects in the parts and excessive stresses during assembly and use. This report gives an overview of design, manufacturing and testing processes of MLCCs focusing on elements related to cracking problems. The existing and new screening and qualification procedures and techniques are briefly described and assessed by their effectiveness in revealing cracks. The capability of different test methods to simulate stresses resulting in cracking, mechanisms of failures in capacitors with cracks, and possible methods of selecting capacitors the most robust to manual soldering stresses are discussed.
Technical Library | 2009-05-21 13:41:05.0
Failure due to board flex cracks persists as the dominant failure mode in multi-layer ceramic capacitors (MLCC). (...) This paper is intended to show the impact of temperature cycling, high-temperature life tests, and multiple bend exposures to the MLCC with this flexible termination.
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