4 Layer PCB Fabrication

Alcanta PCB can produce services designed specifically for multilayer circuits, such as 4 layer PCB. These PCBs include green solder mask and white screen printing layer. This is our best value when ordering large quantities of 4-ply boards, with low cost and quantity discounts per square meter. Multilayer board has many advantages over double-sided board. They can be designed more compact, can greatly improve noise immunity, and are easier to deploy.

The emergence of Multilayer PCB is due to the development and change of electronic industry. With the passage of time, electronic functions become more and more complex, requiring more complex PCB. Unfortunately, PCB is limited by noise, stray capacitance and crosstalk, so some design constraints need to be followed. These design considerations make it difficult to achieve a satisfactory level of performance for single or double sided PCBs – hence the birth of multilayer PCBs.

Packaging the power supply of double-layer PCB into a small part of the size, multi-layer PCB is becoming more and more popular in electronic products. They are available in a variety of sizes and thicknesses to meet their ever expanding application needs, with variations ranging from four to twelve layers. The number of layers is usually even because odd layers can cause problems in the circuit, such as warpage, and production costs are no longer cost-effective. Most applications require four to eight layers, although applications such as mobile devices and smartphones tend to use about twelve layers, and some professional PCB manufacturers boast that they can produce nearly 100 layers of Multilayer PCB. However, due to the extremely low cost efficiency, it is difficult to see a multilayer PCB with such a multilayer.

Higher layers and higher technology PCB

Our best choice is 4 layer or 8 layer PCB, but you can count on high-quality, high-tech circuit boards up to 16 layers. You can immediately quote 1-16 layers of Multilayer PCB, and use a variety of materials, copper counterweight, screen printing and solder mask options, you can quote in alcantar PCB to track the quotation and order history.

We offer immediate prices for all RoHS compliant surface treatments, as well as high-end features such as blind and buried holes, controlled dielectrics and controlled impedances that we use in high-tech multilayer PCBs. Some of the printed circuit board functions provided by Alcanta PCB are listed below.

Lamination (Multilayer PCB only)

In order to produce multilayer PCB, glass fiber sheet (called prepreg) alternately injected with epoxy resin is laminated with conductive core material under high temperature and high pressure by hydraulic press. Pressure and heat cause the prepreg to melt and bond together. After cooling, the obtained material follows the same manufacturing process as the double sided PCB. The following is more detailed information about the lamination process with 4-layer PCB as an example:

For 4-layer PCB with 0.062 inch thickness, we usually start with 0.040-inch-thick copper-clad FR4 core. The core has been imaged in the inner layer, but now a prepreg and an outer copper layer are required. The prepreg is referred to as “grade B” glass fiber. It is not rigid until heat and pressure are applied. Therefore, it is allowed to flow during curing and to bond the copper layers together. Copper is very thin foil, usually 0.5 ounces. (0.0007 in.) or 1 oz (0.0014 in.) thick, i.e. added to the outside of the prepreg. The stack is then placed between two thick plates and placed in a laminating press (the press cycle varies with various factors, including material type and thickness). For example, the 170tg FR4 material commonly used in many parts is pressed at 300 psi at 375 ° f for 150 minutes. After cooling, the material is ready for the next process.

Drill hole

PCB design usually requires a certain number of holes for connecting components, linking copper layers together or installing PCB in its housing.

The holes are drilled using an advanced precision drilling system using integral carbide tools designed to quickly remove chips from highly abrasive materials. Depending on the volume to be processed, holes are usually drilled through 2-3 panels at a time. According to the data submitted by the designer, especially the NC drilling file, the precise hole size and position are programmed into the drilling machine. (Tip: early designers often forget to send NC drilling files – ignoring this can cause manufacturing delays.) Some packages require you to export this file separately from the Gerber file export, but the manufacturer does.

Thin aluminum is used as “entry material” and cardboard is used as “export material”. This keeps the drill straight and reduces burr when copper foil passes through PCB. The size of the hole is usually 5 mils larger than the final electroplated through-hole size required to allow copper plating into the hole while maintaining the hole size within tolerance after plating.

Of course, the manufacturing of 4 layer PCB needs more than these steps. Its manufacturing engineering is very precise and needs many procedures to complete.