by Semiconductor Assembly Explained
Semiconductor assembly refers to the process of packaging individual semiconductor die or chips after they have been manufactured through wafer fabrication. This is a crucial step that protects the delicate silicon chips and enables their use in electronic devices. There are several key aspects to semiconductor assembly:
– Dicing: The silicon wafers containing dozens or hundreds of identical die are first sliced into individual chips using a diamond saw blade. This “dicing” process separates the chips for further packaging.
– Die Attachment: The bare semiconductor die are then attached to a substrate such as a lead frame or substrate using epoxy or other adhesives. This attaches and secures each chip for the subsequent assembly stages.
– Wire Bonding: Thin gold or aluminum wires only microns in width are used to connect the bond pads on each chip to the lead frame or substrate using thermosonic or thermocompression bonding. This electrically connects each die.
– Encapsulation: A protective mold compound such as epoxy resin or plastic is used to encapsulate the assembled chip. This seals and protects the chip from environmental factors and physical damage.
– Terminal Attachments: For lead frame-based packages, the leads are formed and trimmed before final attachment of the external connector pins. For other packages external terminals such as balls or pins are attached.
– Marking/Serialization: Unique identification marks such as lot codes or serial numbers may be applied for traceability through laser marking, inkjet printing or other methods.
– Singulation/Trimming: Individual units are cut or split from the lead frames or substrates during this final packaging step to complete assembly of each singulated device.
Reliability Testing is Crucial
Once packaged, Semiconductor Assembly and Testing Services chips must undergo rigorous testing to evaluate quality and reliability before use. Testing screens for defects and ensures each device will function as designed over its intended lifespan. Some key testing procedures include:
– Electrical Testing: Packaged chips have their electrical properties, functions and acceptable parameter ranges tested using automatic test equipment (ATE). This verifies operation.
– Accelerated Life Testing: Highly accelerated life testing subjects parts to extreme conditions such as high temperature to induce early failures. This checks long-term reliability.
– Burn-In Testing: Parts are “stressed” at typical maximum operating conditions for an extended period to screen for infant mortality failures.
– Environmental Testing: Tests identify weaknesses such as exposure to humidity/temperature cycling, mechanical shock/vibration, or power/noise reliability.
– Qualification Testing: Rigorous testing is done on qualification units to verify processes under normal and worst-case limits before full production.
Only chips and devices that pass all testing within specification limits are deemed functioning and reliable for use. This protects end customers from premature product failures. Assembly and testing forms a crucial backbone for semiconductor manufacturing and quality.
Outsourcing Trends in Semiconductor Assembly and Testing
With rising costs of owning and operating semiconductor fabrication and assembly facilities, many chip companies outsource some or all post-fab frontend operations:
– Outsourced Assembly and Test (OSAT): Leading independent providers like JCET, ASE, Amkor offer full turnkey assembly, packaging and testing services to fabless chip designers.
– Foundry Model: IDMs like Intel, TSMC operate semiconductor foundries for hire, while others like GlobalFoundries provide outsourced wafer fabrication services.
– Specialized Services: Numerous niche assembly and test houses focus on specific technologies like MEMS, sensor assemblies, advanced SiP modules or provide specialized testing capabilities.
– Regional Capabilities: Asia remains dominant with Taiwan and China major hubs for OSAT due to infrastructure investments. But local testing options emerge based on proximity to fabless customers.
– Capacity on Demand: Outsourcing assembly/test needs for capacities above internal capabilities or during market fluctuations ensures flexibility and faster scale-up times.
Trends like heterogeneous integration, 3D stacking, complex SiP modules and short design cycles further drive outsourcing as internal wafer fabs and assembly lines cannot easily or quickly retool for new package types or provide specialized testing expertise. Outsourcing remains integral to the modern fabless semiconductor assembly and testing services business model
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
