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back-process-flow.md [2026/05/07 16:19] – [Connection between the substrate & the motherboard] arthurback-process-flow.md [2026/05/07 17:40] (current) – [Categorization] arthur
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   * **Foundries** (e.g., TSMC, Samsung Foundry, Intel Foundry) manufacture wafers based on customer designs.   * **Foundries** (e.g., TSMC, Samsung Foundry, Intel Foundry) manufacture wafers based on customer designs.
   * **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.
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 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.
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 ## Back end manufacturing definitions ## Back end manufacturing definitions
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 {{ :elements.png?600|}} {{ :elements.png?600|}}
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 ### Connection between the die and the substrate ### Connection between the die and the substrate
  
-### Category of substrate +{{ ::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/)): 
 +  * **Flip Chip:** Modern method using solder bumps and underfill polymer on chip pads for direct interconnection between the die and the substrate ((https://en.wikipedia.org/wiki/Flip_chip)), 
 +  * **Wire Bonding:** Traditional method using fine wires (Aluminum, Copper, Silver, Gold) to connect die to substrate ((https://en.wikipedia.org/wiki/Wire_bonding)). 
 + 
 +Each method will have a specific process flow with different steps during the manufacturing in the fabrication plant. 
 ### 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