Carbon ink PCB (printed circuit board) is coated on the PCB substrate with carbon-based conductive ink (referred to as carbon ink), cured to form a PCB with a carbon film conductive pattern. Now the market’s requirements for PCB board production costs have dropped repeatedly, and it is a general trend to use carbon oil keys to replace the current expensive gold keys. Carbon oil board is a relatively common surface treatment method for single and double PCBs. Through a series of inspections, tests and aging tests, and other technical processes, the PCB can work reliably for a long time.
1．The composition of carbon oil
Carbon oil is mainly composed of synthetic resin, hardener, and carbon powder.
The synthetic resin plays a role in adhesion (equivalent to a carrier).
The hardener plays the role of curing.
Carbon powder plays a conductive role (graphite powder can be added, but with high cost).
Some suppliers add a little silver oil into the carbon oil to obtain lower resistance and higher conductivity.
2．The resistance of carbon ink
The resistance of carbon oil is generally expressed by square resistance. Some use ohms per square centimeter (Ω/cm²), and some use ohms per square centimeter (Ω/□). Most suppliers now agree to use Ω/□.
Square resistance refers to the resistance value of any square carbon film on the opposite side, which is related to the thickness and composition of the carbon oil. (It can be analyzed from the figure below).
The carbon ink has strong adhesion, peeling resistance, and strong abrasion resistance, which can reach ≥ 1 million times, and the resistance change rate is ≤ 10%. The square resistance of conductive paste is relatively large compared to other metals. The square resistance of the current carbon oil board can generally be controlled at ≤ 20 ohms, but the cost is low with a high-performance cost ratio. The conductive paste is a crucial material for electronic component packaging, electrodes, and interconnection of electronic components. It mainly includes two types: burn-in conductive paste and curing conductive adhesive (conductive ink).
Carbon oil board is mainly used in film circuits, mobile phone soft circuits, medical devices, communication equipment, automotive electronics, smart label RFID, and many other industries. In the circuit board industry, it is mainly used for calculators and remote controls. It can replace copper-plated holes, silver slurry hole fillings, and the copper slurry hole filling process. Environmental protection and the low cost of carbon slurry hole filling is the mainstream trend of the development of circuit boards. Currently, Microsoft uses carbon oil filling holes on the power supply board, which can completely replace the double-layer board with copper-plated holes.
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1. Carbon ink gap:
Since carbon oil has good electrical conductivity, the carbon oil on the finished board needs a gap to ensure that there is no short circuit. Usually, the minimum gap should be 8mil (HOZ bottom copper) and 12mil (1-3oz bottom copper) for the finished product. If opening a film, then the gap should increase.
2. Carbon oil minimum alignment tolerance: +/-6mil
3. The size of the carbon oil window and the gap between the copper pattern: Due to the alignment tolerance and oil leakage and to ensure copper is not exposed, the carbon oil must be 6mil (HOZ bottom copper) or 8mil (1-3OZ bottom copper) larger than the copper pad on one side. Correspondingly, a gap of 6 mil (HOZ bottom copper) and 8 mil (1-3OZ bottom copper) between the carbon oil window and the surrounding copper pattern is required. This is to prevent carbon oil from covering the surrounding copper pattern, to avoid short circuits.
The resistance of carbon oil is only related to its composition and thickness. Therefore, to obtain a satisfactory resistance requirement, we must follow three aspects.
1) A reasonable square resistance carbon oil that meets the process requirements.
2) A reasonable thickness (0.01-0.025mm) should be achieved after printing.
3) Baked fully (oven: 150℃ to 170℃, for 30-60 minutes; infrared oven: 150℃, for 15 minutes).
In the actual operation process, the temperature is high, the time is long, and the square resistance is low. It is important to choose a reasonable temperature and time without affecting the substrate.
The first screen printing carbon oil thickness: 0.3-1.0mil, tolerance: +/-0.3mil. If the thickness of the carbon oil is required to be 1.0mil or more, the carbon oil needs to be reprinted twice. The second reprinted carbon oil thickness: 1.0-2.0mil, tolerance: +/-0.4mil. The second reprint carbon oil film is 3mil smaller than the first, so two sets of tools need to be written on MI.
1. PCB fabrication.
2. Turnkey PCBA: PCB+components sourcing+SMD and through-hole assembly
3. PCB clone, PCB reverse engineering.
PCB or PCBA Files Requests:
1. Gerber files of the bare PCB board
2. BOM (Bill of material) for assembly (please kindly advise us if there is any acceptablecomponents substitution.)
3. Testing Guide & Test Fixtures if necessary
4. Programming files & Programming tool if necessary
5. Schematic if necessary
Global Well Electronic Inc. is a professional PCB solution supplier from Shenzhen, China, integrating PCB circuit board production and processing, STM processing and mounting, PCBA OEM, component purchasing, PCB/PCBA custom design-production- A comprehensive PCB circuit board company with one-stop turnkey service of processing-assembly-finished products. The company has a strong supply chain system, a professional and efficient collaborative team, a sound and complete quality control system, and the business philosophy of honesty and trustworthiness, customer first, and presents the products to everyone with low prices, reliable quality, high-quality service and after-sales service. client.
We provide total PCB solutions from PCB design to final mass production, including PCB fabrication and assembly, component sourcing, solder paste stencils, conformal coatings, and more. Serving the global electronics field, including industrial control, medical electronics, military equipment, power communication, automotive electronics, AI artificial intelligence, smart home and other industries.
Our factory located in Shenzhen, and have almost 300 employees, more than 30 production lines include SMT, DIP, automatic welding, aging test and assembly. We have SMT machines from Japan and Korea, automatic solder paste printing machines, solder paste inspection machine(SPI)12 temperature zone reflow soldering machine, AOI detector, X-RAY detector, wave soldering machine, EM PCB ,dispenser,laser print machine etc., Different line configurations can meet requirements from small sample order to bulk shipment.
Our company has obtained ISO 9001 quality system certification and ISO 14001 system certification. With multi-testingprocedures, our products carry out the quality system standard strictly.
|Order Quantity||1-300,000,30000 Square Meter/Square Meters per Month module electronic board|
|Layer||1,2,4,6,upto 40 layer|
|Material||FR-4,glass epoxy,FR4 High Tg,Rohs compliant,Aluminum,Rogers,etc|
|Shape||Any shape: Rectangular,round,slots,cutouts,complex,irregular|
|Max PCB dimensions||20inch*20inch or 500mm*500mm|
|Thickness||0.2~4.0mm, Flex 0.01~0.25''|
|Thickness tolerance||± 10%|
|Copper thickness||0.5-4 oz|
|Copper thickness tolerance||± 0.25oz|
|Surface finish||HASL,Nickle,Imm Gold,Imm Tin,Imm Silver,OSP etc|
|Solder mask||Green, red,white,yellow,blue,black, Double-sided|
|Silk screen||White,yellow,black,or negative, Double-sided or single-sided|
|Silk screen min line width||0.006'' or 0.15mm|
|Min drill hole diameter||0.01'',0.25mm.or 10 mil|
|Min trace/gap||0.075mm or 3mil|
|Turnkey PCBA||PCB+components sourcing+assembly+package|
|Assembly details||SMT and Thru-hole, ISO lines|
|Lead Time||Prototype: 15 work days. Mass order: 20~25 work days|
|Testing on products||Flying Probe Test, X-ray Inspection, AOI Test, functional test|
|Quantity||Min quantity: 1pcs. Prototype, small order, mass order, all OK|
|Files we need||PCB: Gerber files(CAM, PCB, PCBDOC)|
|Components: Bill of Materials(BOM list)|
|Assembly: Pick-N-Place file|
|PCB panel Size||Min size: 0.25*0.25 inches(6*6mm)|
|Max size: 20*20 inches(500*500mm)|
|PCB Solder Type||Water Soluble Solder Paste, RoHS lead free|
|Components details||Passive Down to 0201 size|
|BGA and VFBGA|
|Leadless Chip Carriers/CSP|
|Double-sided SMT Assembly|
|Fine Pitch to 0.8mils|
|BGA Repair and Reball|
|Part Removal and Replacement|
|Component package||Cut Tape,Tube,Reels,Loose Parts|
Soldering-----Assembling-----ICT-----Function Testing-----Temperature - Humidity Testing
PCBA are packed into plastic bags. Plastic bags are put into small carton. 4 small carton into a big carton.
A big carton: 35×32×40 cm size.
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If you need help on PCB layout, you can contact us and send the board to us. We also provide Reverse Engineering Service.
We have been providing PCB Manufacture for many years in China,and we have rich experience in product production and product assembly.We believe our team will provide high quality and low cost service for you.
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