PCB Tech - Special process of PCB circuit board processing

Special process of PCB circuit board processing

Circuit board PCB processing special process As a person in the PCB profession, it is necessary to be proficient in PCB copy board, PCB planning-related process, after the analysis and summary of the company’s professional PCB copy board personnel, we are professional PCB copy board experts The following special process of PCB processing is obtained, and I hope that it can be helpful to PCB professionals.

Additive Process

Refers to the surface of a non-conductor substrate. With the help of an additional resist, a chemical copper layer is used to directly grow a part of the conductor circuit. The addition method used in PCB copy board can be divided into different methods such as full addition, half addition and partial addition.

Backpanels, Backplanes support plate

A circuit board with a thicker thickness (such as 0.093", 0.125"), which is specially used to connect other boards. The method is to first pierce the multi-pin connector (Connector) in the urgent through hole, but not solder, and wire the wires one by one by winding the wires on the guide pins of the connector through the board. The connector can be pierced into the general PCB copy board. Because the through holes of this special board cannot be soldered, but the hole wall and the guide pin are directly clamped for use, its quality and aperture requirements are very strict, and its order quantity is not very large, and the general circuit board manufacturers are not willing It is not easy to receive such orders, and it has become a kind of high-level professional occupation in the United States.

Build Up Process

This is a new category of thinmulti-layer board practice. The earliest enlightenment was derived from IBM's SLC process, which began trial production at its Yasu factory in Japan in 1989. The method is based on traditional double-sided boards. The outer panel surface is first fully coated with a liquid photosensitive precursor such as Probmer 52. After semi-hardening and photosensitive resolution, a shallow "photo-via" (Photo-Via) communicating with the next bottom layer is made, and then chemical copper and After electroplating copper with a conductive layer added on the entire surface, and after circuit imaging and etching, new-style wires and buried or blind holes interconnected with the bottom layer can be obtained. Repeatedly adding layers in this way will be able to obtain the required number of layers of multi-layer boards. This method can not only eliminate the costly and expensive mechanical drilling costs, but also the aperture can be reduced to less than 10mil. In the past 5 to 6 years, various types of multi-layer board technologies that have broken the traditional and gradually increased layers have been promoted by the U.S., Japan and European companies, which has made these Build Up Processes famous, and there are more than a dozen products on the market. There are so many kinds. In addition to the above-mentioned "photosensitive hole formation"; there are also differences in alkaline chemical biting, laser ablation, and plasma etching for organic plates after removing the copper skin of the hole. Hole formation" approach. In addition, a new type of "Resin Coated Copper Foil" (Resin Coated Copper Foil) coated with semi-hardened resin can be used, and Sequential Lamination can be used to make a thinner, denser, smaller and thinner multilayer board. In the future, diversified personal electronic products will become the world of such real frivolous and small multi-layer boards.

Cermet ceramic powder mixes ceramic powder with metal powder, and then joins the adhesive as a kind of coating, which can be printed on the surface of the circuit board (or on the inner layer) with a thick film or thin film, as a "resistor" cloth Set up to replace the external resistors when assembling.

Co-Firing

A process in which porcelain is mixed into a PCB circuit board (Hybrid), where a small board surface has been printed with various types of precious metal thick film paste (Thick Film Paste), and it is fired at a high temperature. The various organic carriers in the thick film paste are burned away, leaving noble metal conductor lines as interconnecting wires.

The more the crossover is, the three-dimensional crossing of the two wires on the vertical and horizontal plane of the crossover, and the gap between the intersections is filled with insulating medium. Generally, a single-panel green paint surface with a carbon film jumper, or the wiring on the top and bottom of the build-up method is such a "crossover".

Discreate Wiring Board PCB circuit board, double wire board

That is, another version of Multi-Wiring Board is made by attaching a round enameled wire to the board surface and adding through holes. The function of this kind of multi-line board in high-frequency transmission line is better than the flat square circuit formed by etching of general PCB.

DYCOstrate plasma etch hole build-up method

The Build up Process developed by a Dyconex company located in Zurich, Switzerland. The copper foil at each hole of the board surface is first etched away, and then placed in a closed vacuum environment, and filled with CF4, N2, and O2, so that the plasma (Plasma) with extremely high activity is formed by ionization under high voltage. The patented method for etching the substrate at the perforation position and presenting tiny via holes (below 10 mils), its commercial process is called DYCOstrate.

Electro-Deposited Photoresist Electro-Deposited Photoresist, electrophoretic photoresist

A new type of "photoresist" construction method, originally used for "electro-painting" of metal objects with messy appearance, has only recently been introduced to the application of "photoresist". The electroplating method is used to uniformly plate the charged colloidal particles of the optically active charged resin on the copper surface of the PCB circuit board as an anti-etching resist. Mass production has now begun in the direct copper etching process for inner-layer boards. This type of ED photoresist can be placed on the anode or cathode according to different operation methods. It is called "anode type photoresist" and "cathode type photoresist". According to different photosensitive principles, there are two types: "photopolymerization" (Negative Working) and "photographic differentiation" (Positive Working). Now the negative working ED photoresist has been commercialized, but it can only be used as a planar resist, and the through hole cannot be used for the impression of the outer layer board due to the difficulty of photosensitive. As for the "positive ED" that can be used as a photoresist for the outer layer plate (because it is a photosensitive film, the hole wall is insufficiently photosensitive, but it has no effect), and Japanese companies are still stepping up their efforts, hoping to open up commercialization The use of mass production makes the manufacture of thin circuits relatively simple to achieve. This term is also called "Electrothoretic Photoresist" (Electrothoretic Photoresist).

Flush Conductor embedded circuit, flat conductor

A special PCB copy board circuit board that has a flat surface and all conductor lines are pressed into the plate. The single-sided method is to first use the impression transfer method to etch away the copper foil on the semi-cured substrate board to obtain the circuit. Then, the circuit board is pressed into the semi-hardened plate by high temperature and high pressure method, and at the same time, the hardening of the resin of the plate can be completed, and the circuit board is completely flat with the circuit retracted into the outer surface. Generally, a thin copper layer needs to be etched away on the surface of the circuit that has been retracted by this kind of board, so that another 0.3mil nickel layer, 20 microinch rhodium layer, or 10 microinch gold layer are plated. When performing sliding touch, its touch resistance can be lower, and sliding is simpler. However, this method is not suitable for PTH, in order to prevent the through hole from being squeezed during press-in, and it is not easy for this kind of board to reach the surface completely and smoothly, and it cannot be used in high temperature to prevent the resin from swelling and then the circuit is ejected. Appearance. This kind of skill is also called Etch and Push method, and its completed board is called Flush-Bonded Board, which can be used for special purposes such as RotarySwitch and Wiping Contacts.

In the thick film paste (Poly Thick Film, PTF) printing paste of Frit glass frit, in addition to precious metal chemicals, it is necessary to join the glass powder class to play the role of agglomeration and adhesion in the high temperature incineration, so that the printing on the blank ceramic substrate Paste, can form a strong noble metal circuit system.

Fully-Additive Process

The method of electroless deposition of metal (mostly chemical copper) on the completely insulated plate surface to grow selective circuits is called the "full additive method." There is also a less correct statement is the "Fully Electroless" method.