Q&A of PCB

1、Will the quality and thickness of PCB affect the heat dissipation effect？

Heat dissipation effect is mainly affected by circuit design, which determines the heat dissipation .

2、The main reason of boards deformed and turn out.

(1) Boards deformed:

a. Circuit design : such as single trace , uneven distribution of traces

b. The inner stress in the board is excessive

(2) Boards turn out:

a. The holes designed too close , layers between layers are loose after drilling.

b. The microstructure roughness between layers is insufficient, so bonding force is insufficient.

c. The boards are wet due to the environment of fabrication and storage.

3、What kind of thickness for copper ? The finished board thickness how to calculate?

Copper thickness has Hoz ,1oz ,2oz,3oz .general products use Hoz , like a car plate, aerospace military,

communications more than 1oz is commonly used ,to ensure the capacity.

The copper is electrolytic copper , the purity is more than 99.9%.

The finished boards thickness calculate from base material to the surface of copper.

4、How to evaluate a PCB?

According to IPC6010 standard to evaluate the capacity.

5、What is the minimum distance between the via’s PAD and opening PAD?

What is the minimum distance between opening pads to ensure the solder dam?

What is blocking point?

a. The minimum distance between via’s pad and opening pad should greater than or equal to 4mil.

b. To ensure the solder dam, the minimum distance between opening pads needs 7.5mil.

c. Blocking point will add a block area for solder mask in the center of the hole.

6、What is the normal thickness for plating gold finger?

If possible we make the boards with gold finger for ENG gold surface treatment and then the gold

finger no need to plated additional gold?

a. The normal thickness of plating gold finger is 2.54um nickel-gold and the thickness of gold is 0.5-0.75um.

b. Yes, customer can choose whole board with ENG gold and the gold finger no need the other plated, but we will suggest plating hard gold for boards with frequently inserted and removed.

7、About the content of fire rating marking.

Flammability UL94 is the most widely used standard for flammability of plastic materials. It is used to evaluate the ability of materials to extinguish after ignition. There are a variety of ways to judge ,such as burning speed, burning time, ability to resist drops and whether the drop burns

Flame retardant grade of plastics from HB, V-2, V-1 to V-0 incremental step by step:

HB: the lowest grade for flame retardant rating in UL94 standard .

Request for samples of 3 to 13 mm thick, burning speed is less than 40 mm per minute;

For samples less than 3 mm thick, the combustion rate is less than 70 mm per minute, or out in front of the sign of 100 mm.

V-2: Flame extinguishes in 60 seconds after two 10-second combustion tests on the sample, combustion falling down is allowed.

V-1: Flame extinguishes in 60 seconds after two 10-second combustion tests on the sample, combustion falling down is not allowed.

V-0: Flame extinguishes in 30 seconds after two 10-second combustion tests on the sample, combustion falling down is not allowed.