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back-process-flow.md [2026/05/07 16:25] – [Back end manufacturing definitions] arthurback-process-flow.md [2026/05/07 17:40] (current) – [Categorization] arthur
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   * **OSATs (Outsourced Semiconductor Assembly and Test)** (e.g., ASE, Amkor, and JCET) handle packaging, encapsulation, testing, and final assembly.   * **OSATs (Outsourced Semiconductor Assembly and Test)** (e.g., ASE, Amkor, and JCET) handle packaging, encapsulation, testing, and final assembly.
  
 +This division of labor enables specialization but also fragments environmental accountability across borders and corporate entities.
  
-This division of labor enables specialization but also fragments environmental accountability across borders and corporate entities. 
 ## Back end manufacturing definitions ## Back end manufacturing definitions
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 {{ :elements.png?600|}} {{ :elements.png?600|}}
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   * Die (silicon core),   * Die (silicon core),
   * Heat spreader (top metallic layer), which interfaces with cooling solutions to manage thermal output    * Heat spreader (top metallic layer), which interfaces with cooling solutions to manage thermal output 
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 ### Connection between the die and the substrate ### Connection between the die and the substrate
  
-{{ ::fc_wire.png?400|}}+{{ ::fc_wire.png?300|}}
  
 The interconnection method between the die and substrate can also be of two types ((https://www.hqicsubstrate.com/ic-substrates-blog/show/flip-chip-vs-wire-bonding/)): The interconnection method between the die and substrate can also be of two types ((https://www.hqicsubstrate.com/ic-substrates-blog/show/flip-chip-vs-wire-bonding/)):
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 Each method will have a specific process flow with different steps during the manufacturing in the fabrication plant. Each method will have a specific process flow with different steps during the manufacturing in the fabrication plant.
  
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-### Category of substrate  
 ### Connection between the substrate & the motherboard ### Connection between the substrate & the motherboard
  
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 {{ ::lga-bga-pga.png?600 |}} {{ ::lga-bga-pga.png?600 |}}
 +### Categorization
 +
 +**Back end manufacturing** can be categorize between the following groups:
 +  * **LGA:** used by Intel for desktop CPUs. Pins are on the motherboard; CPU has flat contacts. Installation involves alignment and pressure.
 +  * **PGA:** used by AMD for desktop CPUs. Pins are on the CPU, motherboard has receptacles. Installation involves insertion.
 +  * **BGA:** used in mobile devices (laptops, tablets). CPU is soldered directly to the PCB via spherical solder joints. Non-detachable.
 +  * **FC-BGA:** more space-efficient; chip is flipped and soldered directly to PCB ((https://www.sinsmarts.com/blog/industrial-computer-cpu-packaging-methods-lga-pga-and-bga-analysis/)).
 +  * **WLP(Wafer-Level Packaging):** encapsulation occurs before wafer dicing, it is typically used for very small equipment such as headphones ((https://en.wikipedia.org/wiki/Wafer-level_packaging)).
 +
 +Other types of processes exists such as QFN, DFN ((https://en.wikipedia.org/wiki/Flat_no-leads_package)) which are not covered in the first project of naKnow.
 +
 +{{ ::typesencap.png?900 |}}
  
 ## Full process flow for back-end manufacturing ## Full process flow for back-end manufacturing