PCB Tech - Blind hole board production knowledge of Shenzhen circuit board factory

Blind hole board production knowledge of Shenzhen circuit board factory

The most effective way to increase the density of PCB circuit boards is to reduce the number of through holes, and accurately set blind holes and buried holes.

1. Blind hole definition

a: In contrast to through holes, through holes refer to holes drilled through each layer, and blind holes are non-drilled through holes.

b: Blind hole subdivision: blind hole (BLINDHOLE), buried hole BURIEDHOLE (outer layer is not visible); c: distinguished from the production process: blind holes are drilled before pressing, and through holes are drilled after pressing .

2. Circuit board manufacturing method of Shenzhen circuit board factory

A: Drill belt:

(1): Select reference point: select the through hole (ie a hole in the first drill belt) as the unit reference hole.

(2): Each blind hole drilling belt needs to select a hole and mark its coordinates relative to the unit reference hole.

(3): Note that which drill belt corresponds to which layers: the unit sub-hole diagram and drill tip table must be marked, and the names of the front and back must be consistent; the sub-hole diagram cannot appear with abc, and the front is 1st, 2nd Indicates the situation.

Note that when the laser hole is sleeved with the inner buried hole, that is, the holes of the two drill belts are in the same position, you need to ask the customer to move the position of the laser hole to ensure the electrical connection.

B: Shenzhen circuit board factory is producing pnl board edge process hole: ordinary PCB multi-layer circuit board: the inner layer is not drilled;

(1): The rivets gh, aoigh and etgh are all shot after the board is eroded

(2): target hole (drilled hole gh) ccd: the outer layer needs to be copper out, x-ray machine: directly punch out, and note that the long side is at least 11 inches.

Blind hole plate:

All tooling holes are drilled, pay attention to rivets gh; need to be out to avoid misalignment.

(aoigh is also a beer), the edge of the pnl board needs to be drilled to distinguish each board.

3. Film modification:

(1): Indicate that the film has a positive film and a negative film:

General principles: the board thickness is greater than 8mil (without copper) to take the positive film process; the board thickness is less than 8mil (without copper) to take the negative film process (thin plate);

When the line thickness and the line gap are large, the copper thickness at d/f should be considered, not the bottom copper thickness. The blind hole ring can be made 5mil, no need to make 7mil. The inner independent pad corresponding to the blind hole needs to be retained. Holes cannot be made without ring holes.

4. The process of Shenzhen PCB Factory:

The buried-hole board is the same as the ordinary double-sided circuit board.

Blind hole plate, that is, one side is the outer layer:

Positive film process: Single-sided d/f is required, and attention must be paid not to roll the wrong side (when the double-sided bottom copper is inconsistent); when d/f is exposed, the glossy copper surface is covered with black tape to prevent light transmission. Because the blind hole board is made more than two times, the thickness of the finished product is very easy to be too thick. Therefore, the thickness of the board should be controlled and the range of copper thickness should be indicated after etching. After pressing the board, use the x-ray machine to punch out the target holes for the multilayer circuit board.

Negative film process: for thin plates (<12mil with copper) because they cannot be produced in the drawing circuit, they must be produced in the hydrometal drawing, and the hydro drawing cannot separate the current, so it is not possible to do single-sided non-current or drawing according to the mi requirements. Small current. If the positive film process is used, the copper thickness on one side is often too thick, which causes etching difficulties and the phenomenon of thin lines. Therefore, this type of board uses the negative film process.

5. The drilling sequence of through holes and blind holes is different, and the deviation is inconsistent during production

Blind hole plates are more prone to deformation, and it is difficult to open horizontal and straight materials to control multi-layer board alignment and tube spacing. Therefore, only open horizontal or only straight materials when cutting.

For the boarding process of this type of board, attention should be paid to sealing the hole with resin before making the circuit so as not to cause greater damage to the circuit.