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Mail us if you have any questions. We may ship the books from Asian regions for inventory purpose. Clearly written, authoritative, and well organized, this is a practical, up-to-date reference that forms a unique, one-stop handbook for their design and manufacture. The removal of bonding wires has advantages on reliability as wire bonds are prone to failure during operation because of the high intermittent temperature cycling from the junction. Mail us if you have any questions.
Embeds 0 No embeds. No notes for slide. The design of automotive power module should address the performance and reliability issues related to electrical, thermal, and mechanical.
They are the main functional aspects that a power module has to serve. The power devices, module structure, materials, and packaging technologies are responsible for these performances, reliability, cost, volume, and weight. However, the thermal and mechanical performances are mainly dependent on module packaging aspects.
It is generally believed that the electrical performance and reliability are mainly controlled by power switches. The thin-wafer technology, trench gate, and field stop layer are introduced to trade-off conduction and switching losses by which the frequency and efficiency are improved.
Printed on acid-free paper. Library of Congress Cataloging-in-Publication Data. Sheng, William W. Power electronic modules: design and manufacture / William . Summary. Designing and building power semiconductor modules requires a broad, interdisciplinary base of knowledge and experience, ranging from.
The power dissipation results from leakage currents are reduced by the optimization of chip design. At the moment, the standard fourth-generation IGBT technology is widely adopted by various industries. The frequency and switching loss are also optimized by these structures and field stop layer. One of the main objectives of automotive module design is to achieve low parasitic parameters. During the switching, an overshoot voltage V OS , equal to the product of L S and current-varying rate, will be applied on the device terminals.
The speed of automotive modules is much higher than industrial applications, resulting in high V OS and reliability problems.
L S of an IGBT module results from the substrate metal parts, bonding wires, conduct bus bars, control, and auxiliary pins. Design rules for minimizing the parasitic effects are proposed including reductions of current loop geometrical length and area [ 32 ], laminated bus bar, planar chip interconnection by using metal lead or PCB [ 2 , 19 , 32 ].
It is supposed that the commutation loop length and area are valuable indicators of low L S substrate design. Thick and short bus bar and wires are effective to minimize L S of a module. Due to substrate design, this bus bar may not be applicable. Furthermore, the laminated sandwich layout bus bars are verified as effective low L S design solution [ 31 ]. Therefore, L S can be reduced, wire bonds failure is avoided, and the heat transfer efficiency is enhanced significantly by spreading through both sides of the chips. Thermal performance and reliability are of most importance for automotive IGBT modules as the ambient temperature is very high under the hood.
On the other hand, the active power cycling and surging are more frequent than other applications that happen in the acceleration and deceleration stages. Therefore, large passive and active temperature excursions always occur in an automotive module operation.
The abovementioned problems result in serious reliability problems on power module joining and interconnection parts. Reliability and lifetime of a power module is limited by the weakest point of the above parts. Thermal design of IGBT module lies in the chip and packaging structure and materials.
By elevating T jmax of chips, the reliability will be enhanced as the improvement of electrical performance, and the requirement of module design will be mitigated. To enhance reliability and prolong lifetime, power dissipated in chips and parasitic components must be spread with high efficiency, which can be achieved by low R th i-c. Design for low R th j-c is dependent on the optimization of module structure and material. The high thermal conductivity ceramic such as AlN and Si 3 N 4 , and Cu or AlSiC baseplate with optimized thickness, direct cooling structure without using thermal grease are proved effective solutions to reduce the overall R th j-h.
However, the thermal performance should be traded off with reliability, weight, and cost. The direct liquid cooling DLC pin fins can be optimized in terms of efficiency, shape, layout, material, and cost. Lifetime of the module is predicted under a real mission, which shows that it is capable of meeting the requirements with high coolant temperature [ 3 ]. Comparison of Rth j-h between conventional and direct cooling modules a and automotive IGBT module with optimized Al in-line pin fins b. The baseplate-free module can benefit to R th j-h , weight, and cost, and the double-side-cooling structure can increase further the heat transfer efficiency.
The planar and next-generation copper-bonding wires with novel soldering technology are effective solutions to this instability. The novel die attachment technologies such as silver sintering and transient liquid phase sintering TPLS are verified to improve the power cycling capability by orders of magnitude. Improvement of lifetime by copper wire with novel soldering Left , lifetime comparison of modules with soldered and sintered die attach .
The mechanical shock and vibration affect mostly on the conduct bus bar and pins, which happen frequently in the running of an automobile. The strength of contacts should be enhanced in order to meet automotive standard that requires the module to be tested for 2 h per axis at more than 10 g for vibration, and three times at each direction and more than g for shock. The design and manufacture of automotive power module were following industrial power module packaging standard at the beginning.
The conventional structure and technologies were applied in automotive module, which was the sandwich structure including plain baseplate and direct bond copper DBC substrate interconnected by solder reflowing and wire bonding. A typical DLC module integrates liquid-cooling structure such as pin fins into the baseplate, which can flow through coolant without an external heat sink.
Therefore, the traditional thermal interface layer between baseplate and heat sink is eliminated, and the un-uniformity and degradation of thermal grease will be avoided as well. DLC module with pin-fin plate is excellent in delivering higher power than plain base or baseplate-free modules, and the converter system with DLC module is compact and reliable. This will simplify power electronics system without separate cooling circuit, resulting in the reduction of overall cost, weight, and volume of whole vehicle.
However, high-temperature cooling has huge adverse effects on reliability and lifetime of power module, and may result in exceeding of T j max. The direct liquid cooling is generally believed as an efficient thermal management with high cooling efficiency at high-temperature applications. The manufacture complexity and cost of pin-fin baseplate are high compared to plain plate at the moment, and the new technologies are required to integrate DLC structure into external cooling path.
The integrated module and cooling structure eliminates the conventional baseplate and thermal interface layer. The assembly includes a buffer plate with punched holes for releasing the stresses between the cooler and DBA caused by a coefficient of thermal expansion CTE mismatch.
The Al ribbons were used to replace Al wires for improving the reliability and electric parasitic parameters of die interconnections. The state-of-the-art IGBT modules are based on a solder construction for chips attaching to substrate and substrate attaching to baseplate. Investigations have shown that these solder layers constitute the weakness of power semiconductor module as they demonstrate fatigue when exposed to active and passive temperature cycling.
The chips are sintered by silver on substrate, achieving a very high-power cycling capability. The sinter joint is a thin silver layer whose thermal resistance is superior to that of a soldered joint. The pressure contact of bus bar and auxiliary pins results in very low thermal and ohmic resistance and high thermal reliability. The baseplate-free structure has advantages of low volume and lightweight, but a thermal interface layer must be applied to improve the contact between substrate and heat sink, which deteriorates the thermal performance and reliability.
The focus then shifts to manufacturing processes and quality control. The authors outline each key manufacturing operation and its corresponding inspection techniques and include two detailed manufacturing flow charts, one for the standard approach and one for a new all-solder approach. The final section of the book examines actual samples based on four different designs. The authors compare these samples in terms of thermal-electrical performance, thermal-mechanical performance, physical characteristics, and cost.
The growing importance of power modules has led to numerous but scattered journal and conference articles.