PCB Technical - Special process for PCB processing of circuit board

1. Additive process addition

It 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 p.62, No. 47, Journal of circuit board information for details). The addition methods used in circuit boards can be divided into full addition, semi addition and partial addition.

2. Backing plates

It is a kind of circuit board with thick thickness (such as 0.093 ", 0.125"), which is specially used to plug and contact other boards. The method is to first insert the multi pin connector into the pressing through hole without soldering, and then wire one by one in the way of winding on each guide pin of the connector passing through the board. A general circuit board can be inserted into the connector. Because the through hole of this special board can not 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 quantity is not many. General circuit board manufacturers are unwilling and difficult to accept this order, which has almost become a high-grade special industry in the United States.

3. Build up process

This is a thin multi-layer plate method in a new field. The early Enlightenment originated from the SLC process of IBM and began trial production in Yasu factory in Japan in 1989. This method is based on the traditional double-sided plate. The two outer plates are fully coated with liquid photosensitive precursors such as probmer 52. After semi hardening and photosensitive image resolution, a shallow "photo via" connected with the next bottom layer is made, After chemical copper and electroplated copper are used to comprehensively increase 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. In this way, the required number of layers of multilayer board 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 been continuously promoted by manufacturers in the United States, Japan and Europe, making these build up processes famous, 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" approaches such as alkaline chemical biting, laser ablation and plasma etching for organic plates after removing the copper skin at the hole site. In addition, a new type of "resin coated copper foil" coated with semi hardening resin can be used to make thinner, denser, smaller and thinner multilayer boards by sequential lamination. In the future, diversified personal electronic products will become the world of this really thin, short and multi-layer board.

4. Cermet Taojin

The ceramic powder is mixed with metal powder, and then the adhesive is added as a coating. It can be used as the cloth placement of "resistor" on the circuit board surface (or inner layer) in the form of thick film or thin film printing, so as to replace the external resistor during assembly.

5. Co firing

It is a manufacturing process of ceramic hybrid circuit board. The circuits printed with various kinds of precious metal thick film paste on the small board are fired at high temperature. The various organic carriers in the thick film paste are burned, leaving the lines of precious metal conductors as interconnected wires.

6. Crossover crossing

The vertical intersection of two vertical and horizontal conductors on the board surface, and the intersection drop is filled with insulating medium. Generally, carbon film jumper is added on the green paint surface of single panel, or the wiring above and below the layer adding method is such "crossing".

7. Create wiring board

That is, another expression of multi wiring board is formed by attaching circular enamelled wire on the board surface and adding through holes. The performance of this kind of composite 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

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

9. Electro deposited photoresist

It is a new construction method of "photoresist". It was originally used for "electric painting" of metal objects with complex shape. It has only recently been introduced into the application of "photoresist". The system adopts the 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. This kind of ED photoresist can be placed on the anode or cathode according to different operation methods, which is called "anode type electric photoresist" and "cathode type electric photoresist". According to different photosensitive principles, there are two types: negative working and positive working. At present, the negative working ed photoresist has been commercialized, but it can only be used as a planar photoresist. Because it is difficult to photosensitize in the through hole, it can not be used for image transfer of the outer plate. As for the "positive ed" that can be used as a photoresist for the outer plate (because it is a photosensitive decomposition film, although the photosensitivity on the hole wall is insufficient, it has no impact). At present, the Japanese industry is still stepping up its efforts, hoping to carry out commercial mass production, so as to make the production of thin lines easier. This term is also called "electrophoretic photoresist".

10. Flush conductor embedded circuit, flat conductor

It is a special circuit board whose surface is completely flat and all conductor lines are pressed into the plate. The single panel method is to etch part of the copper foil on the semi cured substrate plate by image transfer method to obtain the circuit. Then press the board surface circuit into the semi hardened plate in the way of high temperature and high pressure, and at the same time, the hardening operation of plate resin can be completed, so as to become a circuit board with all flat lines retracted into the surface. Usually, a thin copper layer needs to be slightly etched off the circuit surface into which the board has been retracted, so that another 0.3mil nickel layer, 20 micro inch rhodium layer or 10 micro inch gold layer can be plated, so that the contact resistance can be lower and it is easier to slide when sliding contact is performed. However, PTH should not be used in this method to prevent the through hole from being crushed during pressing in, and it is not easy for this board to achieve a completely smooth surface, nor can it be used in high temperature to prevent the line from being pushed out of the surface after resin expansion. This technology is also called etch and push method, and the finished board is called flush bonded board, which can be used for special purposes such as rotary switch and wiring contacts.

11. Frit glass frit

In addition to precious metal chemicals, glass powder needs to be added to the thick film (PTF) printing paste, so as to give play to the agglomeration and adhesion effect 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

It is a method of growing selective circuits on the completely insulated plate surface by electrodeposition 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

The utility model relates to a circuit for applying precious metal conductive ink on a small porcelain thin base plate by printing, and then burning the organic matter in the ink at high temperature, leaving a conductor circuit on the plate surface, and welding of surface bonded parts can be carried out. The utility model relates to a circuit carrier between a printed circuit board and a semiconductor integrated circuit device, which belongs to thick film technology. In the early days, it was used for military or high-frequency applications. In recent years, due to the high price, the decreasing military, 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 interconnect conductor

Interposer refers to any two layers of conductors carried by an insulating object that can be connected by adding some conductive fillers at the place to be connected. 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.