The most popular silk screen printing process of c

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The process of silk screen printing, carbon ink, silver glue, strippable glue and copper paste (31

31, on contact printing

refers to the printing method in which the printing plate is all pasted on the surface of the piece to be printed, and then the ink is pushed by the scraper, such as the stencil printing method of solder paste. After this process, the full plate rack can be raised and separated from the printing surface at the same time, leaving a solder paste position on the circuit board. The other is off contact printing, which uses tension to make the cloth behind the scraper spring up at the same time when the scraper moves forward and presses down to print, so that the printed pattern can be kept clear. Common plate printing methods belong to this kind. A brief diagram of solder paste printing is used to illustrate the difference between the two. May fall into the passive

32. Plain weave

is a weaving method of cloth used in fingerprinting, that is, when its warp and weft yarns are woven in one over one under, it is called "plain weave". As far as the plate printing method is concerned, the ink leakage of plain woven fabric is the best. Today's popular fabrics are all made of monofilament. Therefore, when the mesh number continues to increase to a certain limit, the silk diameter is too small, resulting in insufficient strength, and it is impossible to weave the cloth required by printing. Generally, when the synthetic fiber (mainly polyester "tedolon") reaches more than 300 mesh/inch (120 mesh/cm), it cannot be used because of insufficient tension. Stainless steel can be compacted to 415 mesh/inch (or 165 mesh/cm) to maintain sufficient tension. At present, only monofilament is used for the plain woven fabric used in the "full inspection of PVC and other construction, municipal engineering and home decoration plastic pipes", so that it is easy to clean, regenerate and weave. However, the multi wire flat weaving method is still used for the weaving of glass fiber cloth in sheet film (pupreg) in order to improve its dimensional stability, facilitate the impregnation and infiltration of resin, and increase the contact area and adhesion

33. Plug pin, plug post

in the circuit board, it usually refers to the male pin part of the connector or socket, which can be inserted into the hole for interconnection, and can also be removed at any time. The word "plugging" sometimes refers to "plug hole", which is a special inhibitor to protect the hole wall for positive etching of the outer plate. Its purpose is the same as that of the capping method. However, the plug hole method can make the outer layer landless, so as to increase the density of wiring

34. Pneumatic stretcher pneumatic stretcher

is a kind of stretching tool made by the plate. It can clamp the cloth from four sides with its clamping mouth, and stretch it slowly and evenly in a "pneumatic" way. It can set and change the required tension. After it reaches the required data, it can be fixed on the frame with glue to become the carrier of line pattern and scraping ink. Because its tension can be controlled from the air pressure, it is more accurate than the "mechanical" tension, which is conducive to the implementation of precision printing. The figure on the left shows the quick clamp and pneumatic pump of the "pneumatic tensioner". The picture on the right shows a lifting tensioning platform with multiple tensioners

35. Poise

is the unit of "viscosity", equal to 1 dyne.sec/cm2. The common unit is centipoise (referred to as CP). The viscosity of commonly used solder paste ranges from 600000 CP to 1million CP

36. Pot life, pot life (processable time)

refers to the double liquid type glue or coating (such as green paint). When the main agent and its special solvent or catalyst (or hardener) are mixed evenly in the container, it becomes a workable material. However, once mixed, the chemical reaction begins until it is almost hardened and can not be used. The period of time available in the container is called pot life or working life

37. Reclaiming regeneration and remanufacture

refers to the process of connecting plates between plate printing. When it is necessary to remove the original stencil on the cloth, and then add a new film, the original film should be softened with chemicals first, and then washed and cleaned with warm water, or the cloth should be further roughened to make the new film stick firmly. This process is called reclaiming

38. In addition, this word also refers to the recycling of some wastes. Relaxation

is an abnormal phenomenon in the tension process. When the "clamp" tension cloth is suddenly tensioned outward, the cloth will temporarily feel relaxed and weak. After a period of reaction, the cloth will gradually show the tension force. This is due to the physical property phenomenon of "cold flow" of the material itself and the process of potential energy redistribution on the whole cloth. Correct "tensioning" steps shall be adopted for site operation. Before the next tensioning, it is necessary to loosen a little, and then pull to a greater tension to reduce the above "Relaxation"

39. Resist paste

prepare carbon powder with uniform particle size into a paste, which can be used as a 20 ~ 50 Ω/sq printed resistor. This printed "resistor" must meet the requirements of uniform thickness and neat edges. However, unless the simple resistor is used in a particularly good environment, its potential performance will gradually deteriorate after being used in a warm and humid environment for a period of time

40. The layout of roadmap lines and parts

refers to the layout of lines and parts printed on the board with non-conductive paint to facilitate service and repair

41. Screen printing

is to use a scraper to scrape out an appropriate amount of ink (i.e. resist) on the cloth with negative patterns, form positive patterns through the local cloth, and print them on the flat copper surface of the substrate to form a covering resist, so as to prepare for subsequent selective etching or electroplating. This method of transfer is commonly known as "printing", and the mainland industry is known as "silk printing". The cloth materials used include polyester, stainless steel, nylon and silk, which have been eliminated. The printing method can also be used in other fields

42. Screenability

refers to that during the plate printing construction, the ink leaks smoothly to the plate or copper surface through the exposed part of the cloth under the action of scraping and pressing, and has good adhesion. If the obtained ink printing pattern also has a good resolution, it can be said that the board, ink, or machinery used have a good "printing ability"

43. Silk screen printing, silk printing

polyester cloth or stainless steel cloth is used as the carrier. The patterns of the positive and negative plates can be transferred to the cloth of the frame in the form of direct emulsion or indirect film to form a plate. As a tool for printing the flat surface, it is called "plate printing" method. The mainland term is referred to as "silk screen"

44. Silver migration

refers to the extension of several mils of silver ion crystals between conductors such as silver paste jumpers or silver paste through holes (sth) in the long-term aging process in a high humidity environment, when there is a DC bias voltage (bias, which means that the potentials of the two conductors are not equal), resulting in deterioration of isolation quality or even leakage, which is called "silver migration"

45. Silver paste

refers to a polymer printing paste composed of 70% fine silver sheets and 30% resin by weight, and a small amount of high boiling point solvent is added as the thinning agent to facilitate the construction of plate printing. Generally, the jumper or through hole added on the board can be connected with silver paste to replace the orthodox PTH, which is specially called sth (silver through hole). This method has the advantages of simple equipment, rapid construction, troublesome waste water and good conduction quality. Its resistance value is only 40m Ω/sq. Generally, the cost of sth is less than two-thirds of that of PTH. It is the darling of low-power simple function circuit boards. It is commonly used in various electronic machines such as remote controllers or desktop computers. Most of the global production of sth plates is concentrated in Southeast Asia, South Korea and other places, and the silver paste used is mainly Japanese, such as Fujikura, Beilu and other brands. In recent years, most board jumpers have been changed into carbon glue, while silver paste is specially used in the field of through-hole double-sided boards. It is not easy for the "silver through hole" technology to achieve customer acceptance. There are often problems such as fracture, looseness and "migration". There is not much literature for reference. The only thing on site is to seek more blessings from ourselves and overcome difficulties based on experience

46. Skip printing, skip plating Miss printing. Features of the hardware of the heat insulation strip tensile testing machine: during the plate printing process, some dead corners of the printing process form missing printing due to poor ink distribution, which is called skipping. This phenomenon is most likely to occur in the conformal coating or green paint printing process. Due to uneven force or insufficient ink volume at the corner of the back of the three-dimensional line, HONGNA technology can not get sufficient green paint supply that has obtained the certification of major domestic electric vehicle lithium battery manufacturers, thus "missing printing" will be formed. As for the missing plating, it means that the plating may occur in the area with strong disturbance of bath liquid or in the area with low current, such as near the orifice and the central part of the hole wall of the orifice, or due to the obstruction of bubbles, the coating is poorly distributed, which gradually makes the coating difficult to grow. See also step plating

47. Snap off bounce height

refers to the height of the cloth from the board surface when printing; That is, the depth at which the scraper is pressed down to reach the plate surface. The other is "off contact distance"

48. Squeegee scraper

refers to the tool that pushes the ink to walk on the plate in lithography. The main material of the scraper is pu (polyurethane polyurethane). The right angle blade can be used to squeeze the ink through the cloth opening and reach the printed plate surface to complete the transfer of its graphics

49. Stencil plate film an indirect plate, which is one of the important tools for plate printing, has a layer of pattern attached to the "ink printing surface" of its cloth, which is called "plate film". This kind of stencil also uses a special photosensitive film, which can be used for image transfer, exposure and imaging from the negative film, then pasted on the cloth, and then baked to remove the protective film to form a plate

50. Tensiometer

when the cloth on the frame has been tensioned and fixed, the "tensiometer" can be used to measure the cloth tension. The unit is newtown/c M. The principle of this measurement is that two fixed support rods are provided on both sides of the base, and there is another short movable support rod in the center, which can freely settle. Under the gravity of the counterweight, this "movable short rod" will have a "falling" action and press on the cloth to be measured, so the "tension" supported by the local cloth can be measured. The correction method is to place the "tensiometer" upright on a flat glass plate, and adjust the surface reading value to zero by an inner hexagon screw at the bottom. Then it can be used to measure the tension of the cloth. (thanks for the guidance of Mr. yangzhixiong of Fansheng.)

51. Thinner thinner

is the "solvent" for dilution. Generally speaking, thinner must not react with diluted solute

52. Thixotropy resistance to vertical flow, shake denaturation, shake solubility, static coagulation

some colloidal substances will appear liquefied and flow when stirred, shaken or vibrated, but when they are completely static, they will appear gelatinous and solidified. This characteristic is called thixotropy. Common ones are ketchup or clay slime. The printing ink used in the circuit board industry, especially green paint or solder paste, must have this "vertical flow resistance", so that the printed three-dimensional "ink" or "paste block" will not collapse or flow away

53. Ultra violet curing (UV curing)

the so-called ultraviolet refers to the light whose wavelength of electromagnetic wave is 200 ~ 400nm (nm refers to nano meter, i.e. m; it can also be written as M μ, mili-m

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