Tag Archives: PCB

The types of printed circuit boards

Posted by on October 22, 2010 No comments

There are normal three basic types of printed circuits boards(PCB) are available.

1. Single-sided PCB

We have just mentioned, the basic PCB, components concentrated in one side, circuits are concentrated on the other side. Because the circuits only in one side, so we call this is single-sided PCB. Now only use this kind in the early stage.

2. Double-sided PCB

The circuits on the both side in this kind board. But with the circuit on both sides, the sides must have the appropriate electrical connections, the circuit between a “bridge” is called the plated through hole (via). PTH is in the PCB, the holes filled or coated with metal, it can be connected to the circuits with both sides. This kind more suitable for use in more complex products than the single-sided PCB.

3. The multilayer PCB

In order to increase the area for routing, multilayer spend more single-sided or double-sided circuit board. The number of multilayer PCB using  more double-sided PCB, and use the insulation between each layer to stick firmly. Board are several layers to represent the separate circuit layers, usually layers are even, and includes the outerside two layers. Most of the boards are 4 to 8 layer structure.

PCB to prevent warping

Posted by on June 19, 2010 No comments

How to prevent the PCB warping? This is the most improtant in the PCB manufacturing preocess.

1. Why is flat circuit board requirement

In the automation plug line, if PCB isn’t flat will cause mispositioning, components can not plug in to the board of the hole and surface mount pad, and even crashing automatically installed machine. After components installed on board, component pins are difficult to cut neatly. Board can not be fitted to the chassis or the machine’s outlet, so, board assembly factory is also very troubled.

2. Warpage standards and test methods

According to the U.S. IPC-6012 (1996 Edition) <<Rigid Printed Boards and performance specifications>> for the maximum allowable surface mount PCB warpage and distortion of 0.75%, other 1.5% of various board permitted. Compare to IPC-RB-276 (1992 Edition) to improve on the requirements of surface mount PCB. Currently, the electronic assembly factory agree with, regardless of double or multi, 1.6mm thickness, is usually 0.70 to 0.75%, and for SMT, BGA’s board, demand is 0.5%.
 
3. Warping board processing:

As in our factory, PCB in the final test will be 100% flatness inspection. Failure of the board who will be singled out, into the oven at 150 degrees and bake under the weight of 3 to 6 hours, and under the weight of natural cooling. And relieving the board out, check in for smoothness, this would save parts of the board, some boards need to bake for two to three times the pressure to leveling.