Buried blind via pcb production introduction

With the electronic products to high-density, high-precision development, the corresponding printed circuit board made the same request. The most effective way to improve pcb density is to reduce the number of through-holes, and the precise setting of blind holes, buried holes to achieve. With the electronic products to high-density, high-precision development, the corresponding circuit board made the same request. The most effective way to improve pcb density is to reduce the number of through-holes, and the precise setting of blind holes, buried holes to achieve.

1. Blind hole definition a: In contrast to the through hole, the through hole refers to all layers through the hole, the blind hole is non-through hole.

                  b: blind hole subdivision: blind hole (BLIND HOLE), buried hole BURIED HOLE (outer layer invisible);

                   c: Distinguish from the production process: (mechanical) blind hole in the pre-press drilling, and through-hole drilling in the post-press.

2. Production methods: a: drill belt:

(1): Select Reference Point: Select the through hole (ie, one hole in the first drill band) as the unit reference hole.

(2): Each hole of a blind hole needs to select one hole and mark the coordinates of the reference hole of the relative unit.

(3): Note which drill band corresponds to which layers: Unit hole chart and drill Tsui table must be marked, and the name before and after the same; can not appear sub-hole map with abc said, and in front with 1st, 2nd Said the situation.

*** Note When the laser hole and the inner buried hole together, that is, two drill holes in the same position, ask the customer to move the laser hole position to ensure the electrical connection.

B: pnl plate edge production process holes:

Ordinary multi-layer board: directly with the film alignment, the inner layer is not drilling; with CCD alignment is bit alignment holes and other tool holes, such as rivet holes, test holes, AOI holes, etc ..

(1): When not drilling, the rivet hole punched out directly.

(2): target hole, x-ray machine punching directly.

Mechanical Blind Plate:

All tooling holes are drilled, pay attention to the best way to use rivets punching production, to avoid alignment error.

3. Film Modify:

(1): indicate the film out of positive, negative:

General principles: thickness greater than 8mil (not even copper) take the positive process;

Thickness of less than 8mil (not even copper) go negative film process (sheet);

When the thick line is large, the thickness of d / f should be taken into account, not the thickness of the bottom copper.

Blind hole ring to do 5mil do not need to do 7mil.

Blind hole corresponding to the inner independent pad to be retained.

Blind hole can not do without ring hole.

4. Process:

Buried plate with the common practice of double-sided plate.

Mechanical blind plate, that is, one side is the outer layer:

Positive process: need to do single-sided lines, D / Ff exposure, light copper surface covered with black tape to prevent light.

Due to the blind plate to do more than two board electricity, electricity, finished extremely easy thickness thick, so pay attention to control the thickness of copper plate thickness, after etching indicate the thickness of copper, thickness range.

After pressing the board with x-ray machine out of the target hole with multi-layer board.

Negative process: for the plate (<12mil> due to process constraints, such as the positive process, often lead to one-sided copper thickness, resulting in etching difficulties, fine lines and other anomalies, so the plate to go negative film process, while the outer circuit Involving two electroplating situation, the surface copper will be partial thick, usually make copper reduction process.

5. Through hole, blind hole drilling sequence is different, the production of inconsistent deviation;

Blind perforated plate easier to produce deformation, open the horizontal material on the PCB alignment and pipe pitch control difficult, so when the material is only open horizontal material or only open material.

6. Laser drill:

LASER DRILL is a blind hole, has its own characteristics:

Aperture size: 4-6 mil

pp thickness <= 4.5mil, calculated as aspect ratio <= 0.75: 1

There are three options pp: LDPP 106 1080; FR4 106 1080; RCC.

7. How to define buried plate need to use resin plug hole:

a. H1 (CCL): H2 (PP)> = 4 thickness ratio

b. HI (CCL) "32 MIL

c. 2OZ and 2OZ laser buried plate; high-thick copper, high tg board required resin sealing.