PCB News - Introduction to some common terms of PCB circuit board

Introduction to some common terms of PCB circuit board

There are many special terms in the PCB circuit board. It is also necessary to know these terms. Here I will explain some professional terms in the PCB circuit board.
1, Autoclave pressure cooker
It is a container filled with high-temperature saturated water vapor and high pressure can be applied. The laminated substrate (Laminates) sample can be placed in it for a period of time to force moisture into the board, and then take out the sample again. Place it on the surface of high-temperature molten tin and measure its "delamination resistance" characteristics. This word is also synonymous with Pressure Cooker, which is commonly used in the industry. In the multi-layer board pressing process, there is a "cabin press method" with high temperature and high pressure carbon dioxide, which is also similar to this type of Autoclave Press.
2, Cap Lamination method
It refers to the traditional lamination method of early multi-layer boards. At that time, the "outer layer" of MLB was mostly laminated and laminated with a thin substrate of single-sided copper skin. It was not until the end of 1984 that the output of MLB increased significantly, and it was changed to the current Copper skin type large or mass pressing method (Mss Lam). This early MLB pressing method using a single-sided copper thin substrate is called Cap Lamination.

3, Caul Plate partition
When the multilayer board is pressed, in each opening of the press, there are often many "books" of bulk materials (such as 8-10 sets) to be pressed in each opening of the press, and each set of "bulk materials" ( Book) must be separated by a flat, smooth and hard stainless steel plate. The mirror stainless steel plate used for this separation is called Caul Plate or Separate Plate. At present, AISI 430 or AISI 630 are commonly used.
4, Crease
In the multi-layer board lamination, it often refers to the wrinkles that occur when the copper skin is improperly handled. Such shortcomings are more likely to occur when thin copper skins below 0.5 oz are laminated in multiple layers.
5, Dent depression
refers to the gentle and uniform sag on the copper surface, which may be caused by the local point-like protrusion of the steel plate used for pressing. If there is a neat drop of the faulty edge, it is called Dish Down. If these shortcomings are unfortunately left on the line after copper corrosion, the impedance of the high-speed transmission signal will be unstable and noise will appear. Therefore, such a defect should be avoided as much as possible on the copper surface of the substrate.
6, Foil Lamination method
Refers to the mass-produced multilayer board, the outer layer of copper foil and film are directly pressed with the inner layer, which becomes the multi-row board large-scale pressing method (Mass Lam) of the multilayer board, which replaces the early tradition of single-sided thin substrates Suppress legal.
7, Kiss Pressure, low pressure
When the multi-layer board is pressed, when the plates in each opening are placed and positioned, they will start to heat up and be lifted up by the hottest layer of the lowest layer, and lift up with a powerful hydraulic jack (Ram) to compress the openings ( Bulk materials in Opening) are bonded together. At this time, the combined film (Prepreg) begins to gradually soften or even flow, so the pressure used for the top extrusion cannot be too large to avoid slippage of the sheet or excessive flow of the glue. This lower pressure (15-50 PSI) initially used is called "kiss pressure". However, when the resin in the bulk materials of each film is heated to soften and gel, and is about to harden, it is necessary to increase to the full pressure (300-500 PSI), so that the bulk materials can be tightly combined to form a strong multi-layer board.
8, Kraft Paper
When laminating (laminating) multilayer boards or substrate boards, kraft paper is mostly used as a heat transfer buffer. It is placed between the hot plate (Platern) of the laminator and the steel plate to ease the heating curve closest to the bulk material. Between multiple substrates or multilayer boards to be pressed. Try to reduce the temperature difference of each layer of the board as much as possible. Generally, the commonly used specifications are 90 to 150 pounds. Because the fiber in the paper has been crushed after high temperature and high pressure, it is no longer tough and difficult to function, so it must be replaced with a new one. This kind of kraft paper is co-cooked with a mixture of pine wood and various strong alkalis. After the volatiles escape and the acid is removed, it is washed and precipitated. After it becomes pulp, it can be pressed again to become rough and cheap paper. material.
9, Lay Up stacking
Before lamination of multilayer boards or substrates, various bulk materials such as inner laminates, films and copper sheets, steel plates, kraft paper pads, etc., must be aligned, aligned, or registered up and down for convenience. It can be carefully fed into the pressing machine for hot pressing. This kind of preparatory work is called Lay Up. In order to improve the quality of the multilayer board, not only this kind of "stacking" work must be carried out in a clean room with temperature and humidity control, but also for the speed and quality of mass production, generally those with less than eight layers use the large-scale pressing method (Mass Lam ) In construction, even "automated" overlapping methods are needed to reduce human errors. In order to save workshops and shared equipment, most factories generally combine "stacking" and "folding boards" into a comprehensive processing unit, so the automation engineering is quite complicated.
10, Mass Lamination (Lamination)
This is a new construction method that abandons the "aligning pin" in the multi-layer board pressing process and adopts multiple rows of boards on the same surface. Since 1986, when the demand for four- and six-layer boards has increased, the pressing method of multi-layer boards has been greatly changed. In the early days, there was only one shipping board on a processing board to be pressed. This one-to-one arrangement has been broken through in the new method. It can be changed to one-to-two, one-to-four, or even more according to its size. The row boards are pressed together. The second of the new method is to cancel the registration pins of various bulk materials (such as inner sheet, film, outer single-sided sheet, etc.); instead use copper foil for the outer layer, and pre-make "targets" on the inner layer board., To "sweep" out the target after pressing, and then drill the tool hole from its center, then it can be set on the drilling machine for drilling. As for the six-layer board or the eight-layer board, the inner layers and the sandwich film can be riveted first with rivets, and then subjected to high-temperature pressing. This simplifies, fast and enlarges the area of the pressing, and can also increase the number of "stacks" (High) and the number of openings (Opening) according to the substrate-based approach, which can reduce labor and double the output, and even automate. This new concept of pressing plates is called "mass pressing plates" or "large pressing plates". In recent years, many professional contract manufacturing industries have emerged in China.
11, Platen hot plate
is a platform that can be moved up and down in the pressing machine required for multilayer board pressing or substrate manufacturing. This kind of heavy hollow metal table is mainly to provide pressure and heat source to the plate, so it must be flat and parallel at high temperature. Usually each hot plate is pre-buried with steam pipes, hot oil pipes or resistance heating elements, and the outer edges of the surroundings also need to be filled with insulating materials to reduce heat loss, and a temperature sensing device is provided to enable temperature control.
12, Press Plate steel plate
refers to the substrate or multi-layer board used to separate each group of loose books (referring to a book composed of copper plate, film and inner layer board) when the substrate or multi-layer board is laminated. This kind of high-hardness steel plate is mostly AISI 630 (hardness up to 420 VPN) or AISI 440C (600 VPN) alloy steel. The surface is not only extremely hard and flat, but also after careful polishing to a mirror-like surface, the flattest substrate or Circuit board. Therefore, it is also called Mirror Plate and Carrier Plate. This kind of steel plate has strict requirements. There should be no scratches, dents or attachments on the surface, the thickness should be uniform, the hardness should be sufficient, and it should be able to withstand the corrosion of chemicals produced during high temperature pressing. After each pressing and dismantling of the board, it must be able to withstand strong mechanical brushing, so the price of this kind of steel plate is very expensive.

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