Some special processes for producing PCB ( I )

1. Additive Process

The chemical copper layer is used for the direct growth of local conductor lines on the non-conductor substrate surface with the assistance of an additional inhibitor.

The addition methods in the circuit board can be divided into full addition, half addition and partial addition and other different ways.

 

2. Backpanels, Backplanes

It’s a thick (such as 0.093″,0.125″) circuit board, specially used to plug and connect other boards. This is done by inserting a multi-pin Connector in the tight hole, but not by soldering, and then wiring one by one in the wire through which the Connector passes through the board. The connector can be separately inserted into the general circuit board. Due to this is a special board, its’ through hole cannot solder, but let hole wall and guide wire direct card tight use, so its quality and aperture requirements are particularly strict, its order quantity is not a lot of, general circuit board factory is not willing and not easy to accept this kind of order, but it has almost become a high grade of specialized industry in the United States.

 

3. BuildUp process

This is a new field of making for the thin multilayer, early enlightenment is derived from IBM SLC process, in its Japanese Yasu plant trial production began in 1989, the way is based on the traditional double panel, since the two outer panel first comprehensive quality such as Probmer52 before coating liquid photosensitive, after half a hardening and sensitive solution like make the mines with the next layer of shallow form “sense of optical hole” (Photo – Via), and then to chemical comprehensive increase conductor of copper and copper plating layer, and after line imaging and etching, can get the new wire and with the underlying interconnection buried hole or blind hole. Repeated layering will yield the required number of layers. This method can not only avoid the expensive cost of mechanical drilling, but also reduce the hole diameter to less than 10mil. Over the past 5 ~ 6 years, all kinds of breaking the traditional layer adopt a successive multilayer technology, in the European industry under the push, make such BuildUp Process, existing products are listed more than more than 10 kinds. Except the “photosensitive pores”; After removing the copper cover with holes, different “hole formation” methods such as alkaline chemical Etching, Laser Ablation, and Plasma Etching are adopted for organic plates. In addition, the new Resin Coated Copper Foil (Resin Coated Copper Foil) coated with semi-hardened resin can also be used to make a thinner, smaller and thinner multi-layer plate with Sequential Lamination. In the future, diversified personal electronic products will become this kind of really thin and short multi-layer board world.

 

4. Cermet

Ceramic powder and metal powder are mixed, and adhesive is added as a kind of coating, which can be printed on the surface of the circuit board (or inner layer) by thick film or thin film, as a “resistor” placement, instead of the external resistor during assembly.

 

5. Co-Firing

It is a process of porcelain Hybrid circuit board. The circuit lines of Thick Film Paste of various precious metals printed on the surface of a small board are fired at high temperature. The various organic carriers in the thick film paste are burned off, leaving the lines of the precious metal conductor to be used as wires for interconnection

 

6. Crossover

The three-dimensional crossing of two wires on the board surface and the filling of insulating medium between the drop points are called. Generally, a single green paint surface plus carbon film jumper, or layer method above and below the wiring are such “Crossover”.

 

7. Discreate-Wiring Board

Another word for multi-wiring board , is made of round enameled wire attached to the board and perforated with holes. The performance of this kind of multiplex board in high frequency transmission line is better than the flat square line etched by ordinary PCB.

 

8. DYCO strate

It’s Switzerland Dyconex company developed the Buildup of the Process in Zurich. It is a patented method to remove the copper foil at the positions of holes on the plate surface first, then place it in a closed vacuum environment, and then fill it with CF4, N2, O2 to ionize at high voltage to form highly active Plasma, which can be used to corrode the base material of perforated positions and produce tiny guide holes (below 10mil). The commercial process is called DYCOstrate.

 

9. Electro-Deposited Photoresist

Electrical photoresistance, electrophoretic photoresistance is a new “photosensitive resistance” construction method, originally used for the appearance of complex metal objects “electrical paint”, recently introduced to the “photoresistance” application. By means of electroplating, charged colloidal particles of photosensitive charged resin are uniformly plated on the copper surface of the circuit board as the inhibitor against etching. At present, it has been used in mass production in the process of copper direct etching of inner laminate. This kind of ED photoresist can be placed in the anode or cathode respectively according to different operation methods, which are called “anode photoresist” and “cathode photoresist”. According to the different photosensitive principle, there are “photosensitive polymerization ” (Negative Working) and ” photosensitive decomposition ” (Positive Working) and other two types. At present, the negative type of ED photoresistance has been commercialized, but it can only be used as a planar resistance agent. Because of the difficulty of photosensitive in the through-hole, it cannot be used for image transfer of the outer plate. As for the “positive ED”, which can be used as a photoresist agent for the outer plate (due to the photosensitive membrane, the lack of photosensitive effect on the hole wall is not affected), the Japanese industry is still stepping up efforts to commercialize the use of mass production, so that the production of thin lines can be more easily achieved. The word is also called Electrothoretic Photoresist.

 

10. Flush Conductor

It’s a special circuit board that is completely flat in appearance and presses all conductor lines into the plate. The practice of its single panel is to use image transfer method to etch part of the copper foil of the board surface on the base material board that is semi-hardened. High temperature and high pressure way will be the board line into the semi-hardened plate, at the same time to complete the plate resin hardening work, into the line into the surface and all flat circuit board. Normally, a thin copper layer is etched off the retractable circuit surface so that a 0.3mil nickel layer, a 20-inch rhodium layer, or a 10-inch gold layer can be plated to provide a lower contact resistance and easier sliding during sliding contact. However, this method should not be used for PTH, in order to prevent the hole from bursting when pressing. It is not easy to achieve a completely smooth surface of the board, and it should not be used at high temperature, in case the resin expands and then pushes the line out of the surface. Also known as Etchand-Push, the finished Board is called Flush-Bonded Board and can be used for special purposes such as Rotary Switch and Wiping Contacts.

 

11. Frit

In the Poly Thick Film (PTF) printing paste, in addition to the precious metal chemicals, glass powder is still needed to be added in order to play the effect of condensation and adhesion in the high-temperature melting, so that the printing paste on the blank ceramic substrate can form a solid precious metal circuit system.

 

12. Fully-Additive Process

It is on the sheet surface of complete insulation, with no electrodeposition of metal method (the vast majority is chemical copper), the growth of selective circuit practice, another expression that is not quite correct is the “Fully Electroless”.

 

13. Hybrid Integrated Circuit

It’s a small porcelain thin substrate, in the printing method to apply the noble metal conductive ink line, and then by high temperature ink organic matter burned away, leaving a conductor line on the surface, and can carry out surface bonding parts of the welding. It is a kind of circuit carrier of thick film technology between printed circuit board and semiconductor integrated circuit device. Previously used for military or high-frequency applications, the Hybrid has grown much less rapidly in recent years because of its high cost, declining military capabilities, and difficulty in automated production, as well as the increasing miniaturization and sophistication of circuit boards.

 

14. Interposer

Interposer refers to any two layers of conductors carried by an insulating body that are conductive by adding some conductive filler in the place to be conductive. For example, in the bare hole of a multilayer plate, materials such as filling silver paste or copper paste to replace the orthodox copper hole wall, or materials such as vertical unidirectional conductive rubber layer, are all interposers of this type.

 

15. Laser Direct Imaging (LDI)

It is to press the plate attached to the dry film, no longer use the negative exposure for image transfer, but instead of the computer command laser beam, directly on the dry film for rapid scanning photosensitive imaging. The side wall of the dry film after imaging is more vertical because the light emitted is parallel to a single concentrated energy beam. However, the method can only work on each board individually, so the mass production speed is much faster than using film and traditional exposure. LDI can only produce 30 boards of medium size per hour, so it can only occasionally appear in the category of sheet proofing or high unit price. Due to the high cost of congenital, it is difficult to promote in the industry

 

16. Laser Maching

In the electronic industry, there are many precise processing, such as cutting, drilling, welding, etc., can also be used to carry out laser light energy, called laser processing method. LASER refers to the “Light Amplification Stimulated Emission of Radiation” abbreviations, translated as “LASER” by mainland industry for its free translation, more to the point. Laser was created in 1959 by the American physicist t.h. moser, who used a single beam of light to produce Laser light on rubies. Years of research have created a new processing method. Apart from the electronics industry, it can also be used in medical and military fields

 

17. Micro Wire Board

The special circuit board with PTH interlayer interconnection is commonly known as MultiwireBoard. When the wiring density is very high (160 ~ 250in/in2), but the wire diameter is very small (less than 25mil), it is also known as the micro-sealed circuit board.

 

18. Moulded Cirxuit

It’s using three-dimensional mold, make Injection molding or transformation method to complete the process of stereo circuit board, called the Moulded circuit or Moulded system connection circuit

 

19 . Muliwiring Board ( Discrete Wiring Board)
It’s using a very thin enameled wire, directly on the surface without copper plate for three-dimensional cross-wiring, and then by coating fixed and drilling and plating hole, the multi-layer interconnect circuit board, known as the “multi-wire board”. This is developed by PCK, an American company, and is still produced by Hitachi with a Japanese company. This MWB can save time in design and is suitable for a small number of machines with complex circuits.

 

20. Noble Metal Paste

It is a conductive paste for thick film circuit printing. When it is printed on a ceramic substrate by screen printing, and then the organic carrier is burned away at high temperature, the fixed noble metal circuit appears. The conductive metal powder added to the paste must be a noble metal to avoid the formation of oxides at high temperatures. Commodity users have gold, platinum, rhodium, palladium or other precious metals.

 

21. Pads Only Board

In the early days of through-hole instrumentation, some high-reliability multilayer boards simply left the through-hole and the weld ring outside the plate and hid the interconnecting lines on the lower inner layer to ensure sold ability and line safety. This kind of extra two layers of the board will not be printed welding green paint, in the appearance of special attention, quality inspection is very strict.

At present due to the wiring density increases, many portable electronic products (such as mobile phone), the circuit board face leaving only SMT soldering pad or a few lines, and the interconnection of dense lines into the inner layer, the interlayer is also difficult to mining height are broken blind hole or blind hole “cover” (Pads-On-Hole), as the interconnect in order to reduce the whole hole docking with voltage large copper surface damage, the SMT plate also are Pads Only Board

 

22. Polymer Thick Film ( PTF)

It’s the precious metal printing paste used in the manufacture of circuits, or the printing paste forming a printed resistance film, on a ceramic substrate, with screen printing and subsequent high temperature incineration. When the organic carrier is burned away, a system of firmly attached circuit circuits is formed. Such plates are generally referred to as hybrid circuits.

 

23. Semi-Additive Process

It is to point to on the base material of insulation, grow the circuit that needs first directly with chemical copper, change again electroplate copper means to continue to thicken next, call “Semi-Additive” process.

If the chemical copper method is used for all line thickness, the process is called “total addition”. Note that the above definition is from the * specification ipc-t-50e published in July 1992, which is different from the original ipc-t-50d (November 1988). The early “D version “, as it is commonly known in the industry, refers to a substrate that is either bare, non-conductive, or thin copper foil (such as 1/4oz or 1/8oz). Image transfer of negative resistance agent is prepared and the required circuit is thickened by chemical copper or copper plating. The new 50E does not mention the word “thin copper”. The gap between the two statements is large, and the readers’ ideas seem to have evolved with The Times.

 

24.Substractive Process

It’s the substrate surface of the local useless copper foil removal, the circuit board approach known as “reduction method”, is the mainstream of the circuit board for many years. This is in contrast to the “addition” method of adding copper conductor lines directly to a  copperless substrate.

 

25. Thick Film Circuit

PTF (Polymer Thick Film Paste), which contains precious metals, is printed on the ceramic substrate (such as aluminum trioxide) and then fired at high temperature to make the circuit system with metal conductor, which is called “thick film circuit”. It’s a kind of small Hybrid Circuit. The Silver Paste Jumper on single-sided PCBS is also thick-film printing but does not need to be fired at high temperatures. The lines printed on the surface of various substrates are called “thick film” lines only when the thickness is more than 0.1mm[4mil], and the manufacturing technology of such “circuit system” is called “thick film technology”.

 

26. Thin Film Technology
It’s the conductor and interconnecting circuit attached to the substrate, where the thickness is less than 0.1mm[4mil], made by Vacuum Evaporation, Pyrolytic Coating, Cathodic Sputtering, Chemical Vapor Deposition, electroplating, anodizing, etc., which is called “thin film technology”. Practical products have Thin Film Hybrid Circuit and Thin Film Integrated Circuit, etc

 

 

27. Transfer Laminatied Circuit

It’s a new circuit board production method, using a 93mil thick has been processed smooth stainless steel plate, first do the negative dry film graphics transfer, and then the high-speed copper plating line. After stripping the dry film, the wire stainless steel plate surface can be pressed at high temperature to the semi-hardened film. Then remove the stainless steel plate, you can get the surface of the flat circuit embedded circuit board. It can be followed by drilling and plating holes to obtain interlayer interconnection.

CC – 4 coppercomplexer4; Edelectro-deposited photoresist is a total additive method developed by American PCK company on special copper-free substrate (see the special article on the 47th issue of circuit board information magazine for details).Electric light resistance IVH (Interstitial Via Hole); MLC (Multilayer Ceramic) (local inter laminar through hole);Small plate PID (Photo imagible Dielectric) ceramic multilayer circuit boards; PTF (photosensitive media) Polymer thick film circuit (with thick film paste sheet of printed circuit board) SLC (Surface Laminar Circuits ); The surface coating line is a new technology published by IBM Yasu laboratory, Japan in June 1993. It is a multi-layer interconnecting line with Curtain Coating green paint and electroplating copper on the outside of the double-sided plate, which eliminates the need for drilling and plating holes on the plate.