Introduction to the special processing of the hott

Introduction to the special process of PCB processing of circuit board

1. Additive process addition method

refers to the direct growth process of local conductor lines with chemical copper layer on the surface of non-conductor substrate with the help of additional resistance agent (see the Journal of circuit board information, No. 47, p.62 for details). The addition methods used in circuit boards can be divided into full addition, semi addition and partial addition

2. Backplanes support plate

is a kind of circuit board with relatively thick thickness (such as 0.093 ", 0.125"), which is specially used to plug and connect other boards. The method is to insert the multi pin connector into the pressing through hole first, but do not solder, and then wire it one by one in the way of winding on each guide pin where the connector passes through the board. A general circuit board can be inserted into the connector. Because of this special board, the through hole cannot be soldered, but the hole wall and guide pin are directly clamped for use, so its quality and aperture requirements are particularly strict, and its order volume is not many. Generally, circuit board manufacturers are unwilling and difficult to accept this order, which has almost become a high-grade specialized industry in the United States

3. Build up process add layer process

this is a thin multi-layer board method in a new field. The earliest enlightenment is from the SLC process of IBM, which was put into trial production in Yasu factory in Japan in 1989. This method is based on the traditional double-sided board. The two outer surfaces are fully coated with liquid photosensitive precursors such as probmer 52. After semi hardening and photosensitive imaging, a shallow "photo via" connecting with the next bottom layer is made, After chemical copper and electroplated copper are added to the conductor layer, and after line imaging and etching, new wires and buried holes or blind holes interconnected with the bottom layer can be obtained. The multilayer board with the required number of layers can be obtained by adding layers repeatedly. This method can not only avoid the expensive mechanical drilling cost, but also reduce the hole diameter to less than 10mil. In the past five to six years, various kinds of multilayer board technologies that break the tradition and adopt layer by layer have made such build up processes famous under the continuous promotion of American, Japanese and European industry, and there are more than ten kinds of products on the market. In addition to the above "photosensitive pore forming"; There are also different "pore forming" ways for organic plates, such as alkaline chemical biting, laser ablation, and plasma etching, after removing the copper coating at the hole site. In addition, a new type of "resin coated copper foil" coated with semi hardening resin can also be used to make thinner, denser, smaller and thinner multilayer boards by using sequential lamination. In the future, diversified personal electronic products will become the world of this really light, short and multi-layer board

4. Cermet ceramic gold

mix ceramic powder with metal powder, and then add adhesive as a kind of coating. It can be printed on the surface (or inner layer) of the circuit board in the form of thick film or thin film, which can be used as the cloth placement of "resistors" to replace the external resistors during assembly

5. Co firing

is a manufacturing process of ceramic hybrid circuit boards. Circuits with various kinds of precious metal thick film pastes printed on small boards are burned at high temperature. All kinds of organic carriers in the thick film paste are burned, leaving precious metal conductor lines as interconnection wires

6. Crossover crossing, overlapping

the vertical intersection of two wires vertically and horizontally on the board, and the intersection drop is filled with insulating medium. Generally, adding carbon film jumpers on the surface of single panel green paint, or wiring above and below the layer adding method, are such "crossover"

7. Create wiring board loose wiring circuit board, double wiring board

is another expression of multi wiring board, which is formed by attaching round enameled wire to the board surface and adding through holes. The performance of this kind of double circuit board in high-frequency transmission line is better than the flat square circuit formed by etching general PCB

8. Dycosttrate plasma etching hole increasing layer method

is a build up process developed by a dyconex company located in Zurich, Switzerland. It is a patented method to etch the copper foil at each hole on the plate surface first, then place it in a closed vacuum environment, and fill CF4, N2, O2, so that ionization can be carried out under high voltage to form plasma with high activity, which is used to etch the substrate at the hole position, and small pilot holes (below 10mil) appear. Its commercial process is called dycostrate

9. Electro deposited photoresist, electrophoretic photoresist

is a new construction method of "photoresist". It was originally used in the "electric paint" of metal objects with complex shapes, but it has only recently been introduced into the application of "photoresist". The system adopts electroplating method to evenly coat the charged colloidal particles of optically sensitive charged resin on the copper surface of the circuit board as an anti etching inhibitor. At present, it has been used in mass production in the direct copper etching process of inner plate. According to different operation methods, this kind of ED photoresist can be placed on the anode or cathode respectively, which is called "anode type electric resistance" and "cathode type electric resistance". According to the different principles of its photosensitive computer, which can timely control the experimental process, display the experimental force and experimental curve, and operate simply and reliably, there are two types of "photosensitive polymerization" (negative working) and "photosensitive decomposition" (positive working). At present, the negative working ed photoresist has been commercialized, but it can only be used as a planar photoresist. Due to the difficulty of photosensitivity in the through hole, it cannot be used for image transfer of the outer plate. As for the "positive ed" that can be used as a photoresist for outer plates (because it is a photosensitive film, the photosensitivity on the hole wall is insufficient, but it has no effect). At present, Japanese manufacturers are still stepping up their efforts, hoping to carry out commercial mass production, so that the production of thin lines is easier to achieve. This word is also called "electrophoretic photoresist"

10. Flush conductor embedded circuit, stick flat conductor

is a special circuit board with an overall flat surface, and all conductor circuits are pressed into the plate. The single panel method is to etch part of the copper foil on the semi cured substrate board by image transfer method to get the circuit. Then press the circuit board surface into the semi hardened plate in the way of high temperature and high pressure, and at the same time, the hardening operation of the plate resin can be completed, so as to become a circuit board with the circuit line retracted into the surface and all flat. Usually, a thin copper layer needs to be slightly etched off the circuit surface into which this board has been shrunk, so that another 0.3mil nickel layer, 20 inch rhodium layer, or 10 inch gold layer can be plated, so that when sliding contact is performed, its contact resistance can be lower and it is easier to slide. However, this method is not suitable for PTH, so as to prevent the through hole from being crushed during pressing, and it is not easy for this kind of board to achieve a completely smooth surface, and it cannot be used in high temperature, so as to prevent the line from being pushed out of the surface after resin expansion. This technology is also known as the etch and push method, and the finished board is called the flush bonded board, which can be used for special purposes such as rotaryswitches and wiring contacts

11. Frit glass melt

in addition to precious metal chemicals, glass powder needs to be added to the printing paste of poly thick film (PTF), so as to exert the effect of coagulation and adhesion in high-temperature incineration, so that the printing paste on the blank ceramic substrate can form a solid precious metal circuit system

12. Full additive process

is a method of growing selective circuits on the surface of completely insulated plates by electrodeposited metal method (most of which are chemical copper), which is called "full addition method". Another incorrect statement is the "full electroless" method

13. Hybrid integrated circuit

is a circuit that applies precious metal conductive ink in the form of printing on a small ceramic thin substrate, and then burns away the organic matter in the ink through high temperature, leaving a conductor circuit on the board surface, which can be used for the welding of surface bonded parts. It is a kind of circuit carrier between printed circuit board and semiconductor integrated circuit, which belongs to thick film technology. In the early stage, it was used for military or high-frequency applications. In recent years, due to the high price, the military decline, and the difficulty of automatic production, coupled with the increasing miniaturization and precision of circuit boards, the growth of this hybrid is much lower than that in the early years

14. Interposer interconnection conductor

refers to any two-layer conductor carried by an insulating object, which can be connected by adding some conductive fillers at the place to be connected, which is called interposer. For example, if the bare holes of multi-layer plates are filled with silver paste or copper paste to replace the orthodox copper hole wall, or materials such as vertical unidirectional conductive adhesive layer, they all belong to this kind of interposer

15. Laser direct imaging, LDI laser direct imaging

is to press the board that has to ensure a constant feeding amount to the dry film. Instead of using negative film exposure for image transfer, the computer commands the laser beam and directly carries out rapid scanning photosensitive imaging on the dry film. Because it emits a single beam of parallel light with concentrated energy, the side wall of the dry film after imaging can be more vertical. However, this method can only work on each board separately, so the speed of mass production is far less than that of using negatives and traditional exposure. LDI can only produce 30 medium-sized boards per hour, so it can only occasionally appear in prototype proofing or high unit price boards. Due to the congenital high cost, it is difficult to promote in the industry

16, laser machining

there are many precision machining in the electronic industry, such as cutting, drilling, welding, welding, etc., which can also be carried out with the energy of laser light, which is called laser machining. The so-called laser refers to the abbreviation of "light amplification stimulated emission of radiation. Some levels of products may be dedicated to excellent athletes". In the mainland industry, it is translated as "laser" for its free translation, which seems to be more relevant than transliteration. Laser was produced by American physicist Iman in 1959 by shooting a single beam of light onto ruby. Over the years, research has created a new processing method. In addition to the electronic industry, it can also be used in medical and military fields

17. Micro wire board micro encapsulated wire (encapsulated wire) board

the circular cross-section enameled wire (glued wire) attached to the board surface is a special circuit board that completes the interconnection between layers through PTH. It is commonly known in the industry as multiwire board "multi wire board". When the wiring density is very large (160 ~ 250in/in2) and the wire diameter is very small (below 25mil), it is also called micro encapsulated circuit board

18. Molded circuit modeling three-dimensional circuit board

using three-dimensional mold to complete the process of three-dimensional circuit board by injection molding or transformation method, which is called molded circuit or molded interconnection circuit. The figure on the left is the schematic diagram of MIC completed by two shots

19. Multiwiring board (or discrete wiring board)

refers to the multi-layer interconnection circuit board obtained by using extremely fine enameled wire to conduct three-dimensional cross wiring directly on the board surface without copper foil, and then after gluing and fixing, drilling and plating holes, which is called "composite board". This is developed by American PCK company and is still produced by Hitachi. This kind of Mwb can save design time and is suitable for a small number of models with complex lines (there is a special article in the 60th issue of the Journal of circuit board information)

20. Noble metal paste

is a conductive paste for thick film circuit printing. When it is printed on the porcelain substrate by plate method, and then the organic carrier is burned away at high temperature, there is a fixed precious metal circuit. The conductive metal powder added to this printing paste must be precious metal