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pcb_manufacturing [2026/05/27 16:46] – [2. inner layer printing and etching] sophiepcb_manufacturing [2026/05/29 12:31] (current) – [15. surface finish] sophie
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 # Manufacturing processes of multilayer Printed Circuit Boards (PCB) # Manufacturing processes of multilayer Printed Circuit Boards (PCB)
  
-This page is dedicated to explaining the process flow of multilayer PCB manufacturing. The image bellow gives an overview of this flow [(https://www.ncabgroup.com/wp-content/uploads/2015/10/02-NCAB_Group_Seminars_How-to-make-a-PCB_2_0_150925.pdf)]. It is important to note that this flow is adapted depending on the type of PCB (single sided, double sided, or multilayer). +This page aims to explain the manufacturing process flow of multilayer PCB manufacturing. {{ref>fig_manuf_flow}} gives an overview of this flow. It is important to note that this flow is adapted depending on the type of PCB (single sided, double sided, or multilayer). 
  
- unpopulated 
  
-<figure center|fig_label>+<figure center|fig_manuf_flow>
 {{ ::capture_d_ecran_2026-05-20_134249.png?direct&800|}} {{ ::capture_d_ecran_2026-05-20_134249.png?direct&800|}}
-<caption>Manufacturing flow of a multilayer unpopulated PCB</caption>+<caption>Manufacturing flow of unpopulated multilayer PCBs [(https://www.ncabgroup.com/wp-content/uploads/2015/10/02-NCAB_Group_Seminars_How-to-make-a-PCB_2_0_150925.pdf)]</caption>
 </figure> </figure>
  
 - -
-## 0. substrate/board fabrication 
- 
-TBA  
-FR4 CCL  
- 
------------------------------------ 
-\\ 
  
 ## 1. board cutting ## 1. board cutting
  
-The board (copper clade laminate sheet) is cut and its edges are soften. +The board is cut and its edges are soften. 
  
----------------------------------------+-------------------------------------- 
 +-
 ## 2. inner layer printing and etching  ## 2. inner layer printing and etching 
  
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 ## 15. surface finish  ## 15. surface finish 
  
-The surface finish can either be ENIG (most common) or tin immersion (often chosen for applications using press fit pins). +The surface finish can either be ENIG, tin immersion, or HASL. The ENIG surface finish is the most common one and tin immersion is often chosen for applications using press fit pins. 
  
 **Electroless Nickel and Immersion Gold (ENIG) ** **Electroless Nickel and Immersion Gold (ENIG) **
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 <figure center|legend> <figure center|legend>
 {{ :capture_d_ecran_2026-05-21_142815.png?direct |}} {{ :capture_d_ecran_2026-05-21_142815.png?direct |}}
-<caption> Nickel and gold depositions on the panel coated with solder mask by the ENIG process </caption>+<caption> Nickel and gold depositions on the panel which is already coated with solder mask by the ENIG process </caption>
 </figure> </figure>
  
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 This type of surface finish is quite common as the surface is made of a material similar to the one used to solder the components. The first step is to clean to surface. Then, the panel is put into a molted solder bath (with a controlled content of copper): the solder attach itself to copper (which are the areas where solder is needed – other copper areas are covered by the solder mask). Then hot air is blowed onto the surface to remove any excess of solder. The PCB is then cleaned to remove any remaining solder solution.  This type of surface finish is quite common as the surface is made of a material similar to the one used to solder the components. The first step is to clean to surface. Then, the panel is put into a molted solder bath (with a controlled content of copper): the solder attach itself to copper (which are the areas where solder is needed – other copper areas are covered by the solder mask). Then hot air is blowed onto the surface to remove any excess of solder. The PCB is then cleaned to remove any remaining solder solution. 
  
----------------------------------------+-------------------------------------- 
 +-
 ## 16. profile ## 16. profile
  
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 ## 17. tests and inspection ## 17. tests and inspection
  
-**electrical test**+**17.1. electrical test**
  
 This step is important to check if the circuit has the right connexions: we are looking for any unexpected short- or open-circuit that would translate a wrong functioning of the PCB. Two method exists to do so: the flying probe test (suitable for smaller volumes and prototypes: each electrical net is tested individually) and the bed of nail or fixture machine (suitable for large batches: all electrical nets are tested simultaneously). The 4-wire kelvin test can also be conducted, in addition of the previous one to check net continuity and resistance.  This step is important to check if the circuit has the right connexions: we are looking for any unexpected short- or open-circuit that would translate a wrong functioning of the PCB. Two method exists to do so: the flying probe test (suitable for smaller volumes and prototypes: each electrical net is tested individually) and the bed of nail or fixture machine (suitable for large batches: all electrical nets are tested simultaneously). The 4-wire kelvin test can also be conducted, in addition of the previous one to check net continuity and resistance. 
  
-** final inspection**+** 17.2. final inspection**
  
 Then each PCB must be inspected to check that there are no remaining defaults in their functioning. Visual checking and and a wide range of other tests are performed to identify any remaining damage on the board.  Then each PCB must be inspected to check that there are no remaining defaults in their functioning. Visual checking and and a wide range of other tests are performed to identify any remaining damage on the board. 
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- +[comment]: <> (
-## Input & outputs during the manufacturing processes (to remove from this page, and to be added later in the LCI page) +
  
  
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 |  activation  |  immersing the surface in catalyst colloid to attach it to the surface sites  |  |  | |  activation  |  immersing the surface in catalyst colloid to attach it to the surface sites  |  |  |
  
 +)
  
 ## References ## References
  
 ~~REFNOTES~~ ~~REFNOTES~~