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pcb_manufacturing [2026/06/05 16:49] – [15. Surface finish] mariepcb_manufacturing [2026/06/05 23:52] (current) – [2. Inner layer printing and etching] sophie
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 ** 2.4. Developpment ** ** 2.4. Developpment **
  
-In previous steps, specific parts of the resist film have been polymerized through UV light exposure. In this step, the unwanted part of the film (unexposed) will be removed to reveal the copper. It could be either an additive (the exposed part is removed) or a negative (unexposed areas are removed) development. Negative development is the most common method. +In previous steps, specific parts of the resist film have been polymerized through UV light exposure. In this step, the unwanted part of the film will be removed to reveal the copper. The development process can be described as either positive (the exposed resin is dissolved by the chemical developer) or negative (the unexposed resin is dissolved by the chemical developer). In PCB manufacturing, the negative development process is predominantly used. 
  
  
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 ## 15. Surface finish  ## 15. Surface finish 
  
-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. +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.  This step is important because it allows customers to add components to the PCBs and prevents copper oxidation.
  
 **Electroless Nickel and Immersion Gold (ENIG) ** **Electroless Nickel and Immersion Gold (ENIG) **
  
-This step is important because it allows customers to add components to the PCBs and prevents copper oxidation. This process is very complexes.  +The ENIG process is very complex.  
-First, the panel goes into a series of chemical bath (a first one – “activator” – to clean and prepare the surface for nickel deposition, the second is an electroless nickel bath, the third one is a immersion gold bath).+The panel goes into a series of chemical baths: a first one, an “activator”, to clean and prepare the surface for nickel deposition, a second, which consists of an electroless nickel bath, and one being an immersion gold bath.
 Gold is applied in a very thin layer (less than 1µm) to protect the nickel from oxidation.  Gold is applied in a very thin layer (less than 1µm) to protect the nickel from oxidation. 
  
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 **V-socre** **V-socre**
  
-Rotating blade on the upper and lower part of the panel creating a “V-shape” pattern where we want the separation of two PCB to be. The depth of the V-shaped lines is closely controlled. +Rotating blade on the upper and lower part of the panel creating a “V-shape” pattern where we want the separation of two PCB to be. The depth of the V-shaped lines is closely controlled. The separation itself will be performed later in the supply chain.
  
 ** Routing** ** Routing**
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 **17.1. 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 connections: we are looking for any unexpected short- or open-circuit that would translate to 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.
  
 ** 17.2. 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 a wide range of other tests are performed to identify any remaining defect on the board. 
  
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