IGBT Module Manufacturing & Failure Analysis Process Seon Kenny (IFKOR QM IPC) Sep-11-2018
Table of Contents 1 2 IGBT Module manufacturing process Failure Analysis process for IGBT module 2
Table of Contents 1 2 IGBT Module manufacturing process Failure Analysis process for IGBT module 3
IGBT Module Manufacturing Process
IGBT Module manufacturing : Module overview auxiliary terminal IGBT/diode chip lid screw nut wire bonds Silicon (insulation) gel power terminal frame glue DBC (Direct Bond Copper) Cu/Al2O3 substrate Cross-sectional view of module baseplate (Cu or AlSiC) solder 5
IGBT Module manufacturing : Production steps production flow 6
IGBT Module manufacturing : Chip soldering Ensure proper adhesion, electrical and thermal contact between the semiconductor chips and DBC substrates. Process sequence: Imprinting Pick and Place Chip soldering Cleaning Imprinting - Scraper pressure, velocity Layer thickness measurements Laser profilometer control of the appropriate thickness of Solder the Paste soldering Printerpaste after imprinting. DBC substrate card Master card before imprinting Master card after imprinting 7
IGBT Module manufacturing : Chip soldering Pick-and-place - Implementation of single chips, NTC(Negative Temperature Coefficient), or substrate resistor etc on the DBC substrate. Before pick-and-place After pick-and-place Pick-and-place 8
IGBT Module manufacturing : Chip soldering Chip soldering - Soldering time, soldering temperature, gas/pressure Soldering batch oven 9
IGBT Module manufacturing : Chip soldering Cleaning - Removal of impurities that appeared during the soldering 10
IGBT Module manufacturing : Card wire bonding Electrical contacting between electronic components and DBC substrates First bonding step: from DBC contact areas to electronic component Electrical tests of every single substrates Visual inspection under light microscope Wire bonding Single bonded substrates 11
IGBT Module manufacturing : System soldering Ensure proper adhesion and thermal contact between the DBC substrate and the baseplate for an efficient thermal dissipation Soldering on baseplate X-Ray inspection Soldering oven Assembly station Assembly principle X-ray unit Wired circuits soldered on base plates X-ray picture 12
IGBT Module manufacturing : System assembly Mounting of the frame onto the base plate Before After 13
IGBT Module manufacturing : Frame wire bonding Electrical contacting between DBC substrates and outer metallic leads on the frame Second bonding step: Frame connectors-to-dbc and DBC-to-DBC bonding - Bonding force, bonding time, ultrasonic energy - Shear force tests of bonds - Visual inspection of every modules power terminalsto-dbc bonds DBC-to- DBC bonds 14
IGBT Module manufacturing : Final assembly and testing Encapsulating, testing and packing for shipment Silicone potting - Control of the silicone-gel hardness 15
IGBT Module manufacturing : Final assembly and testing Gluing or clipping of the lid Electrical testing of every single module Bar code laser imprinting Final visual inspection Packing for shipment 16
Table of Contents 1 2 IGBT Module manufacturing process Failure Analysis process for IGBT module 17
FA(Failure Analysis) Process for IGBT Module
What is Failure Analysis? Determine how or why a semiconductor device has failed. Analyze failed products and clarify the failure causes and mechanism, and provide feedback to the manufacturing and design process not only to prevent reoccurrence in the future and but also to improve manufacturing and product quality. 19
General FA Process Flow for IGBT Modules Receiving Part arrival and registration Checking of the part returned and all necessary information provided FA Process Nondestructive analysis Destructive analysis External visual inspection X-ray inspection Electrical verification Scanning Acoustic Microscopy Mechanical/Chemical preparation Internal visual inspection Fault localization Cross-sectioning SEM/EDX analysis Reporting Report writing Report sending to customer 20
External Visual Inspection of Module Macrophotography Examples for modules at incoming inspection 21
Electrical Verification of Module Electrical measurements with curve tracers up to 5 kv Example shows blocking voltage curves of three systems of same module 22
Mechanical Preparation Removal of lid, frame, housing, power terminals Desoldering of DBC substrate and single dies 23
Chemical Preparation Removal of : - Silicone gel - Imide - Al - Cu - Oxides - Silicone gel removal before after Imide removal before after 24
Internal Visual Inspection(Optical Microscopy) 25
X-ray Inspection 26
Scanning Acoustic Microscopy Investigation of mechanical compounds < Substrate cracked > < System solder delamination > 27
Fault Localization(Infrared Lock-In Thermography) <Observed hot spots on IGBTs> <Hot spot under bond wedges> 28
Cross-sectioning Si chip solder Artifact free cross section by ion beam milling Delamination Cracks 29
SEM and EDX analysis SEM surface inspection and scanning: Material analysis SEM image of a residual Al bond 30