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intro_pcb [2026/06/05 10:22] – [Functional unit and reference flows] marieintro_pcb [2026/07/07 15:56] (current) – [State of the art: environmental impacts] lucas.burlot.ext
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 A Printed Circuit Board is an electronic component at the center of most electronic devices. It allows the power supply and interconnections of different electronic components.   A Printed Circuit Board is an electronic component at the center of most electronic devices. It allows the power supply and interconnections of different electronic components.  
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 ## System definition - Goal and scope ## System definition - Goal and scope
 ### Definition ### Definition
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 PCBs are used to interconnect components soldered on top of the electronic circuit. It distributes both signal and power to assembled components like CPUs, SSDs, RAM slots... Printed Circuit Board are contained in the vast majority of today electronic devices, from PCs to wearables passing by cars, to name a few. PCBs are used to interconnect components soldered on top of the electronic circuit. It distributes both signal and power to assembled components like CPUs, SSDs, RAM slots... Printed Circuit Board are contained in the vast majority of today electronic devices, from PCs to wearables passing by cars, to name a few.
-.+
 ### Types of PCBs ### Types of PCBs
  
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 N/A N/A
 ) )
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 ### Sub-components ### Sub-components
  
 The system is composed of one main part, the board itself, which is composed of a succession of layers of substrate, insulating material and copper traces. When the PCB has a rigid-flex structure, we can consider that it is composed of a set of rigid PCB board, connected via a set of flexible PCB board. The system is composed of one main part, the board itself, which is composed of a succession of layers of substrate, insulating material and copper traces. When the PCB has a rigid-flex structure, we can consider that it is composed of a set of rigid PCB board, connected via a set of flexible PCB board.
-.+
 ### Market overview ### Market overview
  
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   * The end-of-production line multiple tests.   * The end-of-production line multiple tests.
  
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 ### Functional unit and reference flows ### Functional unit and reference flows
  
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 The reference flow is one square meter of manufactured PCB. The reference flow is one square meter of manufactured PCB.
-[comment]: <> (### Distribution and packaging) 
- 
-. 
 ## State of the art: environmental impacts ## State of the art: environmental impacts
  
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   * Limitations   * Limitations
  
-The following table displays the cross-paper comparison at a glance. +The following table displays the cross-paper comparison. 
-^  ^ **Liu 2014**         ^ **Ozkan 2017**          ^ **Grant 2023**      ^ **Le Gargasson 2025**           ^ +^  ^ **Grant 2023**         ^ **Ozkan 2017**          ^ **Liu 2014**      ^ **Le Gargasson 2025**           ^ **Hischier 2007 and updates (Ecoinvent v3.12)** ^ 
-| **Method** | ReCiPe Endpoint | CML 2001 midpoint | CML 2001 midpoint | GWP only (Scope 1+2 / Ecoinvent EF v3.1) |  +| **Method** | ReCiPe Endpoint | CML 2001 midpoint | CML 2001 midpoint | GWP only (Scope 1+2 / Ecoinvent EF v3.1) | EF v3.1 | 
-| **Scope** | Cradle-to-grave | Cradle-to-waste | Board fab + manufacturing | Gate-to-gate / Cradle-to-gate | +| **Scope** | Cradle-to-grave | Cradle-to-waste | Board fab + manufacturing | Gate-to-gate / Cradle-to-gate | Cradle-to-gate | 
-| **Use phase** | Excluded | Excluded | Excluded | Excluded |  +| **Use phase** | Excluded | Excluded | Excluded | Excluded | Excluded | 
-| **Technology** | FR-4, PET, paper, multilayer | FR-4 vs paper P-PCB | FR-4 single-layer | FR-4 PTH, all stackups | +| **Technology** | FR-4, PET, paper, multilayer | FR-4 single-layer | FR-4 vs paper P-PCB | FR-4 PTH, all stackups | FR-4, 6Layers SMT | 
-| **Key hotspot** | Epoxy resin, layer count | Copper (O-PCB); silver (P-PCB) | Etching (FAETP, ODP); copper in board fab | Electricity consumption (~86% of GHG) | +| **Key GWP hotspot** | Epoxy resin, layer count | Etching (FAETP, ODP); copper in board fab | Copper (O-PCB); silver (P-PCB) | Electricity consumption (~86% of GHG) | Electricity (~45% GWP) | 
-| **GWP order of magnitude** | ~3–11 kg CO₂eq/25 cm² | 39.2 kg CO₂e/m² (O-PCB) | 18.6 kg CO₂e/m² | 60–200 kg CO₂e/m² (company range) |+| **GWP order of magnitude** | ~50–500 kg CO₂eq/m² | 18.6 kg CO₂e/m² | 39.2 kg CO₂e/m² (O-PCB) | 60–200 kg CO₂eq/m² (company range) | 200 kg CO2eq/m² |
  
   * **Liu et al. (2014)** — //Future Paper-Based Printed Circuit Boards for Green Electronics: Fabrication and LCA[(liu>[[https://pubs.rsc.org/en/content/articlelanding/2014/ee/c4ee01995d | Liu, Jingping & Yang, Cheng & Wu, Haoyi & Lin, Ziyin & Zhang, Zhexu & Wang, Ronghe & Li, Baohua & Kang, Feiyu & Shi, Lei & Wong, C.P.. Future Paper based Printed Circuit Boards for Green Electronics: Fabrication and Life Cycle Assessment. Energy Environ. Sci.. 7 (2014). https://doi.org/10.1039/C4EE01995D. ]])]//   * **Liu et al. (2014)** — //Future Paper-Based Printed Circuit Boards for Green Electronics: Fabrication and LCA[(liu>[[https://pubs.rsc.org/en/content/articlelanding/2014/ee/c4ee01995d | Liu, Jingping & Yang, Cheng & Wu, Haoyi & Lin, Ziyin & Zhang, Zhexu & Wang, Ronghe & Li, Baohua & Kang, Feiyu & Shi, Lei & Wong, C.P.. Future Paper based Printed Circuit Boards for Green Electronics: Fabrication and Life Cycle Assessment. Energy Environ. Sci.. 7 (2014). https://doi.org/10.1039/C4EE01995D. ]])]//
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 Only carbon intensity is assessed — no other environmental indicators. The company reports are heterogeneous, not audited, and often lack stackup-specific data; some boundary adjustments between years create discontinuities. The affine model rests on only two anchor points (6-layer Ecoinvent entry and one manufacturer's 10-layer self-declaration). Gate-to-gate scope of annual reports is narrower than cradle-to-gate of the model, complicating direct comparison. Manufacturing secrets limit detailed inventory verification Only carbon intensity is assessed — no other environmental indicators. The company reports are heterogeneous, not audited, and often lack stackup-specific data; some boundary adjustments between years create discontinuities. The affine model rests on only two anchor points (6-layer Ecoinvent entry and one manufacturer's 10-layer self-declaration). Gate-to-gate scope of annual reports is narrower than cradle-to-gate of the model, complicating direct comparison. Manufacturing secrets limit detailed inventory verification
  
 +* **Hischier et al. (2007)** — Ecoinvent Report No. 18, Part II: Life Cycle Inventories of Electric and Electronic Equipment — Printed Wiring Boards
  
-#### Impact assesment of PCBs in the EcoInvent database+**Methodology** 
 +This is not an LCA study producing impact results directly, but rather a Life Cycle Inventory (LCI) dataset construction report, feeding the Ecoinvent database (v2.0). The functional unit is 1 m² of unmounted PWB. Impact assessment results are computed downstream by LCA practitioners using characterisation methods of their choice applied to the inventory.
  
-__Impact assessment methods used (EF, ReCiPe, others)__:+**Technologies covered** 
 +Two rigid FR-4 PWB types are inventoried, representative of ICT applications: 
 +* A 6-layer multilayer PWB for surface mount technology (SMT), typical of computer mainboards, graphics cards, etc. 
 +* A 2-layer double-sided PWB for through-hole technology (THT), typical of power supply units or simpler industrial electronics.
  
-The Environnemental Footprint 3.1 method is used here.+For each type, three datasets are constructed: Pb-containing surface finish (HAL Sn-Pb), Pb-free surface finish (mixture of HAL-Sn, immersion tin, immersion silver, and ENIG for SMT; HAL-Sn and immersion silver for THT). Flexible, metal-core, HDI, and specialty PWBs are excluded.
  
-__Environmental impacts associated to the system (indicators)__:+**Life cycle stages covered** 
 +Cradle-to-gate manufacturing : from raw material inputs at the factory gate to the finished unmounted PWB ready for component mounting. Upstream raw material extraction is covered through background Ecoinvent datasets (e.g. copper mining, glass fibre production). Component mounting, use phase, //end-of-life, and recycling// are explicitly excluded from these datasets (treated in other parts of the Ecoinvent report No. 18).
  
-From the EcoIvent data "printed wiring board production, for surface mounting, Pb free"[(ecoinvent>https://ecoquery.ecoinvent.org/3.11/cutoff/dataset/9764/documentation)]+**Flows included in scope** 
 +The inventory is notably comprehensive at the elementary flow level: 
 +Inputs: cores and prepreg (modelled as glass-fibre reinforced polyester), copper foil and copper balls for electroplating, process chemicals (HCl, NaOH, H₂O₂, H₂SO₄, FeCl₃, NaCl, resists, solvents, potassium carbonate, sodium persulfate, ammonium chloride), surface finish metals (Sn, Pb, Ag, Au, Ni depending on variant), solder mask (phenolic resin proxy), electricity (UCTE mix), natural gas and light fuel oil for heat, ultrapure water and process water, transport of inputs (standard distances by lorry and rail), and production plant infrastructure. 
 +Outputs/emissions to air: NMVOC (from resist), acid/base aerosols (HCl, NaOH, H₂O₂, H₂SO₄), Cu and Pb particulates (from electroplating, drilling, HAL), PM2.5 and PM2.5–10, waste heat (100% of electricity input). 
 +Emissions to water: heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) discharged via on-site wastewater treatment plant to river, AOX, COD, BOD, fluoride. 
 +Waste: hazardous waste to incineration, galvanisation sludge to residual material landfill, WWTP sludge, municipal waste to incineration, solvents/resins/paints to hazardous waste incineration. Recycled fractions (copper chloride, paper/plastic scraps, biogenic waste) are excluded per Ecoinvent methodology.
  
-Considering the EF Single Score, the environnemental indicators that contributes the most to at least 80% of the single score are : +**Main results** 
-  - Resource use, minerals and metals +No direct impact results are published in the report itself, but from the inventory structure and the PEF 3.1 calculations:
-  - Climate change +
-  - Eutrophication, freshwater+
  
-__Known hotspots, raw materials, life stage__:+For reference, applying PEF 3.1 in SimaPro to the "printed wiring board production, for surface mounting, Pb free" [[https://ecoquery.ecoinvent.org/3.12/cutoff/dataset/9764/documentation]]  dataset yields approximately 200 kg CO₂eq/m² for GWP, with electricity consumption as the dominant contributor (~45%). For abiotic depletion of elements (ADP-e), the value is approximately 0.032 kg Sb-eq/m², driven by copper (~60%) and gold in the surface finish (~30%).
  
-Taking the Econinvent dataset and documentation and Hischier R. et al. 2007 of the "printed wiring board production, for surface mounting, Pb free surface"[(ecoinvent)]. +**Limitations** 
-The dataset is baseb on a 1.6 mm thick 6-layer PWB with a mixture of several Pb-free surface finishing methods and a weight of a weight of 3.26 kg/m². +The dataset carries several significant limitations, most of which compound over time: 
- +Temporal and technological representativeness: //Primary data sourced from AT&S AG (2006), US EPA (1995/2000), and ZVEI (2006). Given the pace of process optimisation in PCB manufacturing — particularly energy efficiency and chemical management — this nearly 20-year-old data is likely to overestimate current consumption intensities. This is explicitly flagged as a concern//. 
-For 1m², using PEF3.1 and  Simapro. +Electricity mix: The dataset uses the Global electricity mix. Users can adapt the electricity mix by copying and editing the dataset in SimaPro or similar tools, but this requires awareness and additional effort. 
-Electricity consumption is the main contributor to GWP. +Gold and surface finish: As the amount of gold in the PCB is a key contributor to environmental impact, there is a need for precise gold quantity in PCB for an accurate LCA. Also, for PCBs without a gold finish there is an important “hidden burden” by using this dataset, though it is possible to copy the dataset and subtract the gold if needed 
- +. 
-Gold, copper and electricity consumption are the main contributors to the single score. +###Other information on impact assesment :
- +
-* Processes +
-    * PCB factory +
- +
-* Energy use +
-    * Electricity +
- +
-Data needed from manufacturer : +
- +
-* production volume +
-* line capacity +
-* installed power +
-* water usage+
  
 Another known hotspot in the manufacturing process is the etching steps [(ozkan>[[https://link.springer.com/article/10.1007/s11356-017-0280-z | Ozkan, E., Elginoz, N. & Germirli Babuna, F. Life cycle assessment of a printed circuit board manufacturing plant in Turkey. Environ Sci Pollut Res 25, 26801–26808 (2018). https://doi.org/10.1007/s11356-017-0280-z]])]. This manufacturing step requires numerous successive operations, thus having a high energy footprint. It consumes a high quantity of chemical elements, that are present in the resulting waste water. It contributes to almost all the impact for the Fresh Aquatic Ecotoxicity Potential, Ozone Depletion Potential, and  Fresh Aquatic Ecotoxicity Potential indicators. The main contributors to these impacts are the incineration of copper and the chloride acid consumption. Another known hotspot in the manufacturing process is the etching steps [(ozkan>[[https://link.springer.com/article/10.1007/s11356-017-0280-z | Ozkan, E., Elginoz, N. & Germirli Babuna, F. Life cycle assessment of a printed circuit board manufacturing plant in Turkey. Environ Sci Pollut Res 25, 26801–26808 (2018). https://doi.org/10.1007/s11356-017-0280-z]])]. This manufacturing step requires numerous successive operations, thus having a high energy footprint. It consumes a high quantity of chemical elements, that are present in the resulting waste water. It contributes to almost all the impact for the Fresh Aquatic Ecotoxicity Potential, Ozone Depletion Potential, and  Fresh Aquatic Ecotoxicity Potential indicators. The main contributors to these impacts are the incineration of copper and the chloride acid consumption.
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 * Type of surface finish * Type of surface finish
  
-__Main source of uncertainty__: 
-About the Ecoinvent PWB dataset : 
-Time and technological representativeness of this dataset is probably very low as it is sourced from AT&S AG (2006), US EPA (2000) and ZVEI (2006). 
-  
-PCB technologies as well as manufacturing technologies might have change or been optimized since then.  
- 
-As electricity consumption is a key contributor to environmental impact, there is a need for up-to-date electricity intensity of PCB production.  
-Electricity location is an important factor, providing datasets with the most common location (China, South Est Asia, EU, USA, …?), though it is currently possible to copy the dataset and adapt the electricity mix of if the location is known. 
  
-Considering finish separately + By proposing a parametric LCA, like choosing between finish types and electricity mixes, we should allow easier and better assesment of the PCB.
-As the amount of gold in the PCB is a key contributor to environmental impact, there is a need for precise gold quantity in PCB for an accurate LCA.  +
-Also, for PCBs without a gold finish there is an important “hidden burden” by using this dataset, though it is possible to copy the dataset and subtract the gold if needed.+
  
- By proposing a parametric LCA, like choosing between finish types and electricity mixes, we should allow easier and better assesment of the PCB +## Life cycle Inventory (⚠️WORK IN PROGRESS⚠️)
-## Life cycle Inventory+
 [comment]: <> (=> Goal: Define state of the art on life cycle stages to be considered.) [comment]: <> (=> Goal: Define state of the art on life cycle stages to be considered.)
 [comment]: <> (### Database and tools) [comment]: <> (### Database and tools)
-[comment]: <> (#### What are the already existing data (dataset, parametric model, paper, etc.))+[comment]: <> (#### What are the already existing data (dataset, parametric model, paper, etc.)
  
 ### Raw materials ### Raw materials
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 A PCB is composed of a succession of copper, substrate, and pre-preg layers. [(substrate_types>https://www.proto-electronics.com/blog/characteristics-details-and-types-of-pcb-substrates)] A PCB is composed of a succession of copper, substrate, and pre-preg layers. [(substrate_types>https://www.proto-electronics.com/blog/characteristics-details-and-types-of-pcb-substrates)]
  
-The type of substrate material varies depending on the target application of the PCB. The main substrate materials are [(pcb_types_cadence>https://resources.pcb.cadence.com/blog/er-part-1-pcb-substrates-the-truth-about-cost-vs-performance-in-2025)] +The type of substrate material varies depending on the target application of the PCB. The main substrate materials are 
-[(substrate_types)]+[(pcb_types_cadence>https://resources.pcb.cadence.com/blog/er-part-1-pcb-substrates-the-truth-about-cost-vs-performance-in-2025)], 
 +[(substrate_types)],
 [(nextpcb)]: [(nextpcb)]:
   * FR-4:  It is the most common PCB subtrate material. It is composed of epoxy resin reinforced by glass fibers. It has the property to be resistant to fire, water and moisture. The main elements in the glass fibers are silicon dioxide, calcium oxide, aluminum oxide, boron oxide, sodium/potassium oxide, magnesium oxide, iron oxide, titanium oxide, and fluoride, appearing in a decreasing order of concentration[(https://www.viasion.com/blog/what-is-fr4-material-properties-constituents-and-fabricate-steps/)]. The epoxy resin contains an epoxide group, made of two carbon and one oxygen atoms. The most common epoxy material is the DGEBA one, containing carbon hydrogen, chloride and oxygen[(https://resiners.com/blogs/resiners-guide/chemical-formula-of-epoxy?srsltid=AfmBOooBqMoahxKAUb9Ne2xNiQyvRCzmNBMTQ-1Pw-QS64I7LKNr25H2)]. Some derivatives exist, including one resistant for high temperature, using glass with higher fusion temperature [(substrate_types)]. The abreviation FR stands for Flame Retardant.    * FR-4:  It is the most common PCB subtrate material. It is composed of epoxy resin reinforced by glass fibers. It has the property to be resistant to fire, water and moisture. The main elements in the glass fibers are silicon dioxide, calcium oxide, aluminum oxide, boron oxide, sodium/potassium oxide, magnesium oxide, iron oxide, titanium oxide, and fluoride, appearing in a decreasing order of concentration[(https://www.viasion.com/blog/what-is-fr4-material-properties-constituents-and-fabricate-steps/)]. The epoxy resin contains an epoxide group, made of two carbon and one oxygen atoms. The most common epoxy material is the DGEBA one, containing carbon hydrogen, chloride and oxygen[(https://resiners.com/blogs/resiners-guide/chemical-formula-of-epoxy?srsltid=AfmBOooBqMoahxKAUb9Ne2xNiQyvRCzmNBMTQ-1Pw-QS64I7LKNr25H2)]. Some derivatives exist, including one resistant for high temperature, using glass with higher fusion temperature [(substrate_types)]. The abreviation FR stands for Flame Retardant. 
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   * CEM-3: It has a similar composition as CEM-1, with a non-woven glass mat core instead of a paper one. It is more resistant and performant than CEM-1, cheaper but still less performant than FR-4. It is a cheaper alternative for double-sided PCBs [(substrate_types_allpcb>https://www.allpcb.com/allelectrohub/a-comparative-analysis-of-materials-used-for-rigid-pcb-design)].   * CEM-3: It has a similar composition as CEM-1, with a non-woven glass mat core instead of a paper one. It is more resistant and performant than CEM-1, cheaper but still less performant than FR-4. It is a cheaper alternative for double-sided PCBs [(substrate_types_allpcb>https://www.allpcb.com/allelectrohub/a-comparative-analysis-of-materials-used-for-rigid-pcb-design)].
   * Metal substrate: aluminum is often used as metal substrate, sometimes it is copper. It has the advantage to dissipate heat efficiently. It is mostly used for single or double-sided PCBs[(nextpcb)].   * Metal substrate: aluminum is often used as metal substrate, sometimes it is copper. It has the advantage to dissipate heat efficiently. It is mostly used for single or double-sided PCBs[(nextpcb)].
-  * Polytetrafluoroethylene (PTFE): this substrate is made of a plastic with very low resistance, which is adapted for high-frequency applications. The chemical composition is mainly fased on carbon and fluorine atoms. It is also very light and flame resistant [(substrate_types)]. It has also a proprietary alternative called Rogers®.+  * Polytetrafluoroethylene (PTFE): this substrate is made of a plastic with very low resistance, which is adapted for high-frequency applications. The chemical composition is mainly based on carbon and fluorine atoms. It is also very light and flame resistant [(substrate_types)]. It has also a proprietary alternative called Rogers®.
   * Ceramics: this substrate is employed for application requiring high temperature resistance, high thermal conductivity and need for high reliability. It is more expensive and fragile than a FR-4 substrate. It is often made of alumina, aluminum nitride or silicon carbide. [(https://www.allpcb.com/fr-FR/blog/pcb-knowledge/ceramic-pcbs.html)].    * Ceramics: this substrate is employed for application requiring high temperature resistance, high thermal conductivity and need for high reliability. It is more expensive and fragile than a FR-4 substrate. It is often made of alumina, aluminum nitride or silicon carbide. [(https://www.allpcb.com/fr-FR/blog/pcb-knowledge/ceramic-pcbs.html)]. 
  
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 Once the PCB layers are laminated and the copper traces printed, the metal needs to be protected by an additional layer of material. This layer can be composed of: Once the PCB layers are laminated and the copper traces printed, the metal needs to be protected by an additional layer of material. This layer can be composed of:
   * Electroless Nickel Immersion Gold (ENIG)[(https://www.protoexpress.com/kb/enig/)]: it consists in a film of nickel deposited on top of copper pads using electroless plating technique. The nickel is then protected from corrosion and oxidation by a thin layer of gold using immersion methods.   * Electroless Nickel Immersion Gold (ENIG)[(https://www.protoexpress.com/kb/enig/)]: it consists in a film of nickel deposited on top of copper pads using electroless plating technique. The nickel is then protected from corrosion and oxidation by a thin layer of gold using immersion methods.
-  * Elelectroless Nickel Electroless Palladium Immersion Gold (ENEPIG) [(https://www.protoexpress.com/kb/enepig-surface-finish/)]: similar to ENIG finish, with a thiner nickel layer and an additional layer of palladium deposited via electroless plating. It has the advantage to be compatible with almost any kind of PCB. +  * Electroless Nickel Electroless Palladium Immersion Gold (ENEPIG) [(https://www.protoexpress.com/kb/enepig-surface-finish/)]: similar to ENIG finish, with a thiner nickel layer and an additional layer of palladium deposited via electroless plating. It has the advantage to be compatible with almost any kind of PCB. 
   * Hot Air Solder Leveling (HASL)[(https://www.protoexpress.com/kb/hasl-surface-finish/)]: this technique is very affordable and offers a high solderability. It is not compatible with very thin-pitched PCBs. This finish layer is composed of a mixture of eutectic tin and lead. Its application is performed in three steps: the board is immersed in a bath of molten solder. The extra thickness of solder is removed thanks to hot air knives, that are heated above the solder melting temperature. Finally, the board is cleaned to remove all residues remaining after solder soliditication.   * Hot Air Solder Leveling (HASL)[(https://www.protoexpress.com/kb/hasl-surface-finish/)]: this technique is very affordable and offers a high solderability. It is not compatible with very thin-pitched PCBs. This finish layer is composed of a mixture of eutectic tin and lead. Its application is performed in three steps: the board is immersed in a bath of molten solder. The extra thickness of solder is removed thanks to hot air knives, that are heated above the solder melting temperature. Finally, the board is cleaned to remove all residues remaining after solder soliditication.
   * Organic Soderability Preservative (OSP)[(https://www.protoexpress.com/kb/osp-surface-finish/)], [(https://www.sharrettsplating.com/blog/osp-enig-difference/)] is affordable and features a very thin and flat finish. However, it doesn't resist to long storage. It is adapted for fine-pitch design, consumer electronics, and nickel-sensitive applications.  It is composed of azole-based organic compounds like benzotriazoles, imidazoles or benzimidazoles. It is applied by immersing the board into the organic solution, that will form a thin film in interaction with copper atoms.   * Organic Soderability Preservative (OSP)[(https://www.protoexpress.com/kb/osp-surface-finish/)], [(https://www.sharrettsplating.com/blog/osp-enig-difference/)] is affordable and features a very thin and flat finish. However, it doesn't resist to long storage. It is adapted for fine-pitch design, consumer electronics, and nickel-sensitive applications.  It is composed of azole-based organic compounds like benzotriazoles, imidazoles or benzimidazoles. It is applied by immersing the board into the organic solution, that will form a thin film in interaction with copper atoms.