Circuit board proofing manufacturer production process
1. Contact the manufacturer
Need to tell manufacturer of document, technological requirement, quantity above all.
Objective: according to the requirements of engineering data MI, cut into small pieces on the large sheets meeting the requirements. Small pieces of sheet material that meet customer requirements.
Process: plate material → press MI requirement to cut plate → curium plate → beer round corner edge grinding → plate
Objective: according to the engineering data, drill the hole diameter in the corresponding position on the sheet metal with the required size.
Process: lamination pin → upper plate → drilling → lower plate → inspection and repair
Fourth, sink copper
Objective: to deposit a thin layer of copper on the wall of insulating hole by chemical method.
Process: rough grinding → hanging plate → sink copper automatic line → lower plate → dip 1% dilute H2SO4→ thicken copper
5. Graphic transfer
Purpose: graphic transfer is the transfer of images from the production film to the board
Process: (blue oil process) : grinding plate → first side of printing → drying → second side of printing → drying → blasting light → impact → inspection; (dry film process) : hemp plate → pressing film → static setting → alignment → exposure → static setting → impact → inspection
Vi. Graphic electroplating
Objective: graphic electroplating is to electroplate a copper layer of required thickness and a gold nickel or tin layer of required thickness on the exposed copper skin or hole wall.
Process: upper plate → deoiling → washing twice → microerosion → washing → pickling → copper plating → washing → pickling → acid dipping → tin plating → washing → lower plate
Objective: to use NaOH solution to remove anti – electroplating coating layer to expose non – line copper layer.
Process: water film: frame → leaching → washing → scrubbing → passing machine; Dry film: put plate → pass machine
Objective: etching is to use chemical reaction method to corrode the copper layer in non-circuit parts.
Nine, green oil
Objective: green oil is to transfer the green oil film to the board, which can protect the circuit and prevent the tin on the circuit when welding parts.
Process: grinding plate → printing photosensitive green oil → curium plate → exposure → impact; Mill plate → press the first side → dry plate → press the second side → dry plate
Purpose: a character is a token provided for easy identification
Process: green oil terminal curium → cooling static → network adjustment → printed characters → curium
11. Gold plating
Finger purpose: to coat the plug finger with a layer of required thickness of nickel gold layer, so that it has more hardness wear resistance process: upper plate → oil removal → water washing twice → micro corrosion → water washing twice → pickling → copper plating → water washing → nickel plating → water washing → gold plating.
Tinplate? Purpose: tin spraying is to spray a layer of lead tin on the exposed copper surface which is not covered with welding resistance oil, so as to protect the copper surface from corrosion and oxidation and ensure good welding performance. Process: micro erosion → air drying → preheating → rosin coating → solder coating → hot air leveling → air cooling → washing air drying
Objective: through the die stamping or CNC gong machine gong shape molding method of organic gong, beer plate, hand gong, hand cut.
The accuracy of the data gong machine board and beer board is higher, the second hand gong, the lowest hand cutting board can only do some simple shape.
Objective: through the electronic 100% test, detect the open circuit and short circuit which are not easy to be found.
Process: upper die → place plate → test → pass →FQC inspection → unqualified → repair → return test →OK→REJ→ scrap
Objective: through 100% visual inspection of the plate appearance defects, and to repair minor defects, avoid problems and defects of the plate outflow.
Specific workflow: incoming materials → view data → visual inspection → qualified →FQA spot check → qualified → packaging → unqualified → processing → inspection OK.
Circuit board composition
Circuit board is mainly composed of solder pad, throughhole, mounting hole, conductor, components, connector, filling, electrical boundary circuit board industrial area, etc. The main functions of each component are as follows:
Welding pad: used for welding metal hole of component pin.
Through hole: metal through hole and non-metal through hole, in which metal through hole is used for connecting components and pins between layers.
Mounting hole: used for fixing circuit board.
Lead: copper film of electrical network used for connecting pins of components.
Connectors: components used for connecting circuit boards.
Filling: used for copper coating of ground wire network, which can effectively reduce impedance.
Electrical boundary: used to determine the size of the circuit board, all components on the circuit board must not exceed the boundary.
Main categories of circuit boards
Circuit board systems are classified into the following three categories:
We just mentioned that on a basic PCB, the parts are concentrated on one side and the wires on the other. Because the wire only appears on one side, we call the PCB single-sided. Because single panels have many strict restrictions on the design of circuits (because there is only one side, the wiring can not cross * but must go around a separate path), only early circuits used such boards.
The circuit board has wiring on both sides. But to use the two sides of the wire, there must be a proper electrical connection between the two sides. The “bridge” between these circuits is called a guide hole (via). A guide hole is a small, metal-filled hole in a PCB that can be connected to a wire on both sides. Because the double panel is twice as large as the single panel, and because the wiring can be interlaced (it can go around the other side), it is better suited for more complex circuits than the single panel.
[multilayer board] in more complex application requirements, the circuit can be arranged into a multi-layer structure and pressed together, and the through hole circuit is laid between the layers to connect the circuit of each layer.
The inner line
Copper foil substrate first cut into suitable for processing the size of production. Before the substrate pressure film usually need to use brush grinding, micro-corrosion and other methods will be the surface of copper foil do appropriate coasting treatment, and then with appropriate temperature and pressure will dry film photoresist close paste on its. The substrate coated with dry film photoresist is exposed in the uv exposure machine. The photoresist will polymerize when exposed to ultraviolet light in the transparent area of the plate (the dry film in this area will be retained as the etching resist in the later development and copper etching steps), and the line image on the plate is transferred to the dry film photoresist. After tearing off the protective film on the film surface, firstly remove the unilluminated area on the film surface with sodium carbonate solution, and then remove the exposed copper foil corrosion with hydrochloric acid and hydrogen peroxide mixture solution to form a circuit. Finally, the photoresist was removed by sodium hydroxide solution. For the inner circuit board with more than six layers (including), the automatic positioning punch is used to rush out of the riveting datum hole of line alignment between layers.
In order to increase the area that can be wired, multilayer board used more single or double-sided wiring board. Multilayer boards use several double panels and are glued (pressed) by placing an insulating layer between each layer. The number of layers on the board represents the number of independent wiring layers, usually even, and contains the outermost two layers. Most motherboards have 4 to 8 layers, but it is technically possible to have nearly 100 layers of PCB.
Most large supercomputers use fairly multi-layered mainframe boards, but because such computers can be replaced by clusters of many ordinary computers, the use of super-multilayered boards has become obsolete. Because the layers in the PCB are tightly integrated, it’s not always easy to see the actual number, but if you look closely at the motherboard, you might.
With the introduction of surface mount technology, the automatic detection technology of PCB has been applied, and the packaging density of PCB has increased rapidly. Thus, even for a low density, average number of boards, automatic detection of boards is not only basic, but also economical. In the complex circuit board test, two common methods are needle – bed test and double – probe or fly – needle test.
Circuit board maintenance
Circuit board in use, should be regularly maintained to ensure that the circuit board work in a good state and reduce the failure rate of the circuit board. The maintenance of circuit board in use is divided into the following situations:
1. Half-year maintenance:
After a quarterly cleaning of the circuit board dust, can be used to clean the circuit board special cleaning liquid cleaning, the circuit board dust cleaning is completed, with a blower to blow dry the circuit board.
The electronic components have not been observed in the circuit through the trace of high temperature, electrolytic capacitor has no bulging leakage phenomenon, if there should be replaced.
2. Annual maintenance:
After the circuit board dust cleaning.
The electrolytic capacitor on the circuit board capacity sampling, such as found that the electrolytic capacitor capacity is less than 20% of the nominal capacity, should be replaced, the life of the general electrolytic capacitor should be replaced for about 10 years, to ensure the working performance of the circuit board.
3 for the coating of cooling silicone grease high-power device, should check the cooling silicone grease has no dry solid, for the dry solid should be dry solid cooling silicone grease removal, coated with a new cooling silicone grease, to prevent the circuit board in the high-power components due to bad heat and burn.