PCB News - Overview of multilayer circuit board pressing process

Overview of multilayer circuit board pressing process

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 PressureCooker, which is commonly used in the industry. In the multilayer circuit board pressing process, there is a "cabin pressure method" with high temperature and high pressure carbon dioxide, which is also similar to this type of AutoclavePress.
2. CapLamination method
It refers to the traditional laminating method of early multi-layer PCB boards. At that time, the "outer layer" of MLB was mostly laminated and laminated with a single-sided/////multilayer circuit board copper skin, until the end of 1984 MLB Only after the production volume increased significantly, the current copper-skin type large-scale or large-volume pressing method (MssLam) was used. This early MLB pressing method using a single-sided copper thin substrate is called CapLamination.
3. Crease wrinkles
In multi-layer circuit board pressing, 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 0.5oz are laminated in multiple layers.
4. CaulPlate partition
When multi-layer circuit boards are laminated, many "books" of bulk materials (such as 8-10 sets) of the board to be pressed are often stacked between each opening of the press (Opening), 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 CaulPlate or SeparatePlate. Currently, AISI430 or AISI630 are commonly used.

5. FoilLamination copper foil pressing method
Refers to the mass-produced multilayer circuit board, the outer layer of copper foil and film is directly pressed with the inner layer, which becomes the multi-row board large-scale pressing method (MassLam) of the multilayer circuit board, to replace the early single-sided thin substrate Traditional suppression is legal.
6. 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 DishDown. If these shortcomings are unfortunately left on the line after copper etching, 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.

Shenzhen Zhongke Circuit Technology Co., Ltd. is a high-precision PCB multi-layer circuit board manufacturer, focusing on PCB circuit boards, HDI circuit boards, flexible and rigid boards, high frequency boards/high frequency circuit boards, PCB blind buried vias, Long strip boards, extra long circuit boards, long strip circuit boards, double-sided extra long boards, extra long circuit boards, special circuit boards, etc. The factory has imported and domestic plates all year round: the dielectric constant ranges from 2.2 to 10.6.
7, KissPressure kiss pressure, low pressure
When the multi-layer circuit board is pressed, when the plates in each opening are placed in position, they will start to heat up and be lifted up by the hottest layer of the bottom layer, and lifted up with a powerful hydraulic jack (Ram) to compress the openings (Opening) the bulk materials are bonded. At this time, the combined film (Prepreg) begins to gradually soften or even flow, so the pressure used for the top extrusion can not be too large to avoid slippage of the sheet or excessive outflow of the glue. This lower pressure (15-50PSI) initially used is called "kiss pressure". But when the resin in each bulk material is heated to soften and gel, and is about to harden, it is necessary to increase to full pressure (300-500PSI), so that the bulk materials can be tightly combined to form a strong multilayer circuit board.

8. KraftPaper kraft paper
When multi-layer circuit boards or substrate boards are laminated (laminated), 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 circuit boards to be pressed. Try to reduce the temperature difference of each layer of the board as much as possible. Generally, the commonly used specification is 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 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, LayUp stacking
Before lamination of multilayer circuit boards or substrates, various bulk materials such as inner layer boards, films and copper sheets, steel plates, kraft paper pads, etc., need to be aligned, aligned, or registered up and down to prepare Then it can be carefully fed into the pressing machine for hot pressing. This kind of preparatory work is called LayUp. In order to improve the quality of multi-layer circuit boards, 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 the large-scale pressing method (MassLam ) 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" into a comprehensive processing unit, so the automation engineering is quite complicated.
10. MassLamination large pressure plate (laminated)
This is the Multi-layer circuit board pressing process to abandon the "aligning pin" and adopt a new construction method of multiple rows of boards on the same surface. Since 1986, when the demand for four- and six-layer circuit boards has increased, the pressing method of multi-layer circuit 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 put it on the inner layer first. The "target" is pre-made on the top, so that the target is "swept out" after being pressed, and then a tool hole is drilled from the center, and then the hole can be set on the drilling machine for drilling. As for the six-layer circuit board or the eight-layer circuit board, the inner layers and the sandwich film can be riveted first with rivets, and then pressed together at high temperature. 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 method of substrate type, which can reduce labor and double the output, and even automate. This new concept of pressing plate is called "large pressing plate" or "large pressing plate". In recent years, many professional contract manufacturing industries have emerged in China.