Power Electronic Modules: Design and Manufacture

by Sheng; William W.

• ISBN13: 9780849322600
• ISBN10: 084932260X
• Edition: 1st
• Format: Hardcover
• Copyright: 2004-09-29
• Publisher: CRC Press

Summary

Designing and building power semiconductor modules requires a broad, interdisciplinary base of knowledge and experience, ranging from semiconductor materials and technologies, thermal management, and soldering to environmental constraints, inspection techniques, and statistical process control. This diversity poses a significant challenge to engineers, and a book that brings together the essential elements of these technologies is long overdue.Power Electronic Modules: Design and Manufacture fills that void. It covers not only the basic technologies, but also the latest advances in these areas. Organized into three main sections, coverage begins with discussions on the materials used and their key properties, including a comparison of those properties with the requirements of high-performance, cost-effective power modules and the pros and cons of selected materials. 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. 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.

Table of Contents

1 Introduction	1	(6)
References	6	(1)
2 Selection Procedure	7	(4)
References	9	(2)
3 Materials	11	(92)
3.1 Insulating Substrate and Metallization	11	(24)
3.1.1 Selection Criteria	11	(2)
3.1.2 List of Insulating Substrates	13	(6)
3.1.3 Selected Insulating Substrates	19	(5)
3.1.3.1 Alumina (96%, 99%)	19	(1)
3.1.3.2 Aluminum Nitride (AIN)	20	(1)
3.1.3.3 Beryllia (BeO)	21	(1)
3.1.3.4 Silicon Nitride (Si3N4) - Sintered	22	(2)
3.1.4 Metallization on Insulating Substrates	24	(1)
3.1.5 Types of Metallizations	24	(6)
3.1.5.1 Metallization Technologies	24	(1)
3.1.5.2 Types of Metallization	25	(13)
3.1.5.2.1 Thick Film	25	(2)
3.1.5.2.2 Thin Film	27	(1)
3.1.5.2.3 Copper Metallization	27	(3)
3.1.6 Analysis of Copper Metallization Suppliers	30	(5)
References	35	(1)
3.2 Baseplate	36	(9)
3.2.1 Selection Criteria	36	(1)
3.2.2 List of Baseplate Materials	37	(1)
3.2.3 General Summary of Available Base Materials	38	(6)
3.2.3.1 Copper/Molybdenum/Copper Laminate	39	(1)
3.2.3.2 Aluminum/Silicon Carbide Metal Matrix Composite	40	(1)
3.2.3.3 Copper/Molybdenum Matrix	41	(1)
3.2.3.4 Copper/Tungsten Matrix	42	(1)
3.2.3.5 Graphite Fiber-Reinforced Al and Cu Alloys	43	(1)
3.2.4 Production Cost	44	(1)
3.2.5 Compatible Baseplate/Substrate Material Chart	44	(1)
References	45	(1)
3.3 Bonding Material	45	(18)
3.3.1 Pressure Contact	45	(1)
3.3.2 Bonding Material	46	(2)
3.3.3 Selection Criteria for Solder Alloys	48	(10)
3.3.4 Some Useful Information on Non-Pb-Based (or Pb-Free) Solders	58	(1)
3.3.5 Other Components of the Solder Paste	59	(3)
3.3.6 Manufacturing Suitability, Processing, and Facility Conditions	62	(1)
References	63	(1)
3.4 Power Interconnection and Terminal Power Interconnection	64	(5)
3.4.1 Terminals	65	(5)
3.4.1.1 Terminals Formed by Soldering to the Ceramic Metallization or by Integrating with the Case	66	(1)
3.4.1.1.1 Copper Based	66	(1)
3.4.1.1.2 Nickel Based	66	(1)
3.4.1.2 Terminals Formed by Extending and Bending the Ceramic Metallization	67	(2)
References	69	(1)
3.5 Encapsulant	70	(14)
3.5.1 Criteria for Selection	70	(1)
3.5.2 Selection	71	(1)
3.5.3 Descriptions of Encapsulants	71	(4)
3.5.3.1 Silicone Gel Encapsulant	71	(1)
3.5.3.2 Silicone Encapsulant	72	(1)
3.5.3.3 Parylene Coatings	72	(1)
3.5.3.4 Silicon Nitride Coating	73	(1)
3.5.3.5 Acrylic Encapsulant	73	(1)
3.5.3.6 Polyurethane Encapsulant	73	(1)
3.5.3.7 Epoxy Encapsulant	74	(1)
3.5.4 Construction Options	75	(2)
3.5.5 Suppliers	77	(1)
3.5.6 Representative Specifications of Suppliers	77	(7)
References	84	(1)
3.6 Plastic Case and Cover	84	(11)
References	95
3.7 Power Semiconductor Chips	90	(11)
3.7.1 IGBT Chip	90	(8)
3.7.1.1 Body Structure	90	(2)
3.7.1.1.1 Grinding	91	(1)
3.7.1.1.2 Localized Thinning	92	(1)
3.7.1.1.3 Plasma-Assisted Chemical Etch (PACE)	92	(1)
3.7.1.7.4 Spin-Etch	92	(1)
3.7.1.2 Gate Structure	92	(1)
3.7.1.3 Process Control	92	(6)
3.7.2 FRED (Fast Recovery Epitaxial Diode) Chip	98	(3)
References	101	(2)
4 Manufacturing of Power IGBT Modules	103	(102)
4.1 Manufacturing Process	103	(59)
4.1.1 Sorting/Grouping of the IGBT Chips	105	(3)
4.1.1.1 Current Imbalance	105	(2)
4.1.1.2 Junction Temperature Imbalance	107	(1)
4.1.2 Cleaning	108
4.1.2.1 Aqueous Cleaning	110	(1)
4.1.2.2 Semiaqueous Cleaning	111	(1)
4.1.2.3 Solvent Cleaning	112	(3)
4.1.2.4 Key Cleaning Steps for Power Module	115	(2)
4.1.2.4.1 Presolder Cleaning of the Parts	115	(1)
4.1.2.4.2 Postsolder Cleaning of the Subassembly	116	(1)
4.1.2.4.3 Pre-Wire-Bond Cleaning	116	(1)
4.1.2.4.4 Other Cleaning Steps	116	(1)
4.1.2.5 New Dry-Cleaning Method	117	(1)
4.1.2.6 Level of Cleanliness	118
4.1.2.6.1 Coarse Testing	118	(1)
4.1.2.6.2 Analytical Testing	118
4.1.3 Solder Attachment	18	(117)
4.1.3.1 Single-Chamber/Vacuum Soldering	123	(1)
4.1.3.2 Reflow Profile	124	(4)
4.1.3.2.1 Preheat Soak Time and Temperature	126	(1)
4.1.3.2.2 Time above Liquidus	126	(1)
4.1.3.2.3 Peak Temperatures	126	(1)
4.1.3.2.4 Initial Ramp Rate	126	(1)
4.1.3.2.5 Cooling Rate	127	(1)
4.1.3.3 Processing Gas	128	(2)
4.1.3.4 Application of Solder	130	(2)
4.1.3.5 Attachment of Fast-On Terminals	132	(1)
4.1.3.6 Repair/Rework	133	(2)
4.1.3.6.1 Hot Air	133	(1)
4.1.3.6.2 IR Heating	134	(1)
4.1.3.6.3 Conduction	135	(1)
4.1.4 Power Interconnections	135	(10)
4.1.4.1 Ultrasonic Wire Bonding	136	(4)
4.1.4.2 Solder Bump	140	(3)
4.1.4.3 Underfills/Top fills	143	(2)
4.1.4.3.1 Capillary	144	(1)
4.1.4.3.2 Glob	145	(1)
4.1.4.4 Solder Bump Pattern	145	(1)
4.1.5 Electrical and Thermal Testing	145	(18)
4.1.5.1 General	145	(4)
4.1.5.2 Incoming Inspection	149	(3)
4.1.5.2.1 IGBT	149	(2)
4.1.5.2.2 FRED	151	(1)
4.1.5.3 In-Process Production Testing	152	(1)
4.1.5.4 Final Testing for the Finished Module	152	(3)
4.1.5.4.1 Electrical Tests	152	(1)
4.1.5.4.2 Short-Circuit Tests	153	(2)
4.1.5.4.3 SOA Test	155	(1)
4.1.5.5 Test System Considerations	155	(3)
4.1.5.5.1 Mainframe Tester	158	(1)
4.1.5.5.2 Test Station A	158	(1)
4.1.5.5.3 External Tester (9424-KT/B)	158	(1)
4.1.5.5.4 External Tester (3300-SW)	158	(1)
4.1.5.6 Thermal Tests	158	(2)
4.1.5.6.1 Temperature-Sensing Basics	159	(1)
4.1.5.6.2 Sense Junction Calibration	159	(1)
4.1.5.6.3 Thermal Resistance	160	(1)
4.1.5.6.4 Solder Attachment Evaluation and Heating Characterization	160	(1)
4.1.5.7 Test Fixtures	160	(2)
References	162	(1)
4.2 Process Control/Long-Term Reliability	163	(22)
4.2.1 Process Control	163	(1)
4.2.2 Tools	164	(2)
4.2.2.1 Thermal-Electrical Mapping or IR Thermography	164	(1)
4.2.2.2 Thermal-Mechanical Characterization	165	(1)
4.2.3 In-Process Inspection	166	(9)
4.2.3.1 A Partial List of Visual Inspection Criteria for IGBT and FRED Chips	166	(2)
4.2.3.2 Statistical Process Control	168	(7)
4.2.3.2.1 Random Selection	168	(3)
4.2.3.2.2 Sampling Plan	171	(4)
4.2.4 Long-Term Reliability	175	(12)
4.2.4.1 Good Design Practices	176	(1)
4.2.4.2 HALT and HASS	177	(2)
4.2.4.3 Life Tests	179	(4)
4.2.4.3.1 Failure Rate	180	(3)
4.2.4.4 Failure Analysis	183	(2)
References	185	(1)
4.3 Manufacturing Facilities	186	(1)
4.3.1 ESD	187	(6)
4.3.1.1 Test Schedule for ESD-Controlled Products	188	(1)
4.3.1.2 ESD Audit	189	(1)
4.3.2 DI Water	189	(1)
4.3.3 Processing Gas	189	(1)
4.3.4 Chemicals	190	(1)
4.3.5 Electrical Supply	190	(1)
4.3.6 Relative Humidity	190	(1)
4.3.7 Air-Flow and Pressure Differentials	190	(1)
4.3.8 Room Particle Count	190	(1)
4.3.9 Storage Cabinet	191	(1)
4.3.9.1 Passive Parts and Tools	191	(1)
4.3.9.2 Power IGBT /FRED Chips, Subassembled IGBT Parts, and Finished Modules	191	(1)
4.3.10 Cleanroom Accessories and Details	191	(1)
4.3.11 Safety Standards	191	(1)
4.3.12 Environmental Requirements	192	(1)
References	193	(1)
4.4 Manufacturing Flow Charts	193	(12)
4.4.1 Standard Manufacturing Process	194	(1)
4.4.2 Alternative Manufacturing Process	194	(11)
5 Design	205	(54)
5.1 Thermal Management	207	(5)
5.1.1 Stack Structures	207	(1)
5.1.2 Thermal Conduction Analysis	207	(2)
5.1.3 Thermal Stress Analysis	209	(3)
References	212	(1)
5.2 Circuit Partitioning	213	(5)
5.2.1 Thermal Stress between the Chips and the Insulating Substrate	213	(2)
5.2.1.1 Case 1	215	(1)
5.2.1.2 Case 2	215	(1)
5.2.2 Size of Insulating Substrate	215	(2)
5.2.3 Paralleling of IGBT Chips	217	(1)
5.2.3.1 Electrical Matching	217	(1)
5.2.3.2 Thermal Coupling	217	(1)
5.2.4 Cost	217	(1)
References	218	(1)
5.3 Design Guidelines and Considerations	218	(15)
5.3.1 Ceramic Substrate	219	(1)
5.3.2 Metallization Pattern on the Ceramic Substrate	219	(4)
5.3.2.1 Dimensions	220	(1)
5.3.2.2 Guidelines for DBC-A12O3, ABC-A1N, Si3N4 Metallization Pattern	220	(3)
5.3.2.3 Plating	223	(1)
5.3.3 Metal Baseplate	223	(3)
5.3.3.1 Dimensions	223	(2)
5.3.3.2 Baseplate Characteristics	225	(1)
5.3.4 Power Terminals/Fast-On Tabs/Connecting Bridges	226	(3)
5.3.4.1 Dimensions	226	(1)
5.3.4.2 Materials	226	(1)
5.3.4.3 Power Terminals	226	(2)
5.3.4.4 Fast-On Tabs	228	(1)
5.3.4.5 Plating	229	(1)
5.3.4.6 Connecting Bridge	229	(1)
5.3.5 Plastic Case and Cover	229	(1)
5.3.6 Solder Preform	230	(3)
References	233	(1)
5.4 Samples	233	(25)
5.4.1 Estimated Manufacturing Cost	234	(1)
5.4.2 Theoretical Comparison of Design Option	234	(1)
5.4.3 Thermal Behavior of the Samples	234	(24)
5.4.3.1 Thermal Mechanical Characterization	234	(16)
5.4.3.1.1 IGBT /FRED Chips	248	(1)
5.4.3.1.2 Baseplate	249	(1)
5.4.3.2 Thermal Impedance Characterization	250	(8)
References	258	(1)
Appendix A	259	(4)
Power MOSFET	259	(1)
Power Thyristor	260	(1)
Power Rectifier	261	(2)
Appendix B	263	(2)
Barcode and 2D Data Matrix Symbol	263	(2)
Index	265