?The PCB positive and negative film process dispute, or the industry shuffle? - ShenZhen RoyHai Industrial Co., Ltd
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The PCB positive and negative film process dispute, or the industry shuffle?

Time:2020-12-10 16:15Hits:334

Recently, a PCB factory in Shenzhen posted an article on its website attacking the PCB negative process, distorting the facts, misleading consumers, and losing the basic industry responsibility and business bottom line. So what is the reason for a Shenzhen-based company to do such a demeanor behavior? What is the difference between positive and negative film technology? The judges listen to the editor slowly.

1. The difference between positive and negative films:

(1) Positive film: sinking copper-whole board plating (thickening 8 to 10um)-sticking dry film-image plating (thickening to 35um in the finished product)-lead tin plating-etching (the place where lead and tin plating is to be kept, The place covered by the dry film is to be etched away).

(2) Negative film: heavy copper-electroplating of the whole board (thickened directly to the surface copper 35um)-dry film-etching (the place where the dry film is stuck is kept, and the place where the film is not stuck is etched)

(3) Concerning the hazards of negative film process of a Chuangshuo (the following is a screenshot of an article published by Chuangshuo):

After reading these few arguments against negative film technology, people who know about PCB production must have tears. The reasons are as follows:

1. Whether the drilling will be offset or not. The size of the offset depends on the accuracy of the drilling machine itself. The higher the accuracy, the smaller the offset. No factory can drill holes that are exactly the same as the coordinates of the data. Let the accuracy be infinitely close to the coordinate data, this has nothing to do with the positive and negative film;

2. Whether the alignment is offset depends on the accuracy of the alignment. Even the current machine alignment error has nothing to do with the positive and negative film;

3. Whether the welding ring needs to be large enough depends on the thickness of the finished copper of the board. The thicker the copper, the greater the compensation. This is the same for all factories, that is, the positive film will be compensated when the data is made. The size of the compensation depends on Plant equipment capabilities. It's not that the customer's information can be enlarged indefinitely when we take it. The board we make must meet the IPC standard.

4. Regarding the dry film sealing ability of the plug-in hole, there is definitely no problem in the dry film with copper holes sealed to 6.0mm. If the negative film exceeds this hole diameter, it is indeed impossible to make a half hole. Any process has certain shortcomings.

(4) The advantage of the negative film process of a creative theory is its low cost:

Haha, what I don’t know is that a certain creation is an objective evaluation cost issue, but it is actually confusing the audience and giving people the illusion that the use of negatives is to reduce costs. Its heart is punishable! The actual situation is as follows:

1. As a user-centric enterprise, Hangzhou Jiepei Speedy Proofing Factory must consider the cost under the premise of ensuring quality. Poor control of the negative film of the plug-in hole will result in no copper in the hole, resulting in a lot of scrap, so The negative film requirements will be higher,

2. When sinking copper, if a board has 10% of the circuit, we will use the negative film to plate 100% of the entire board with copper, 90% of the surface copper will be wasted and etched away, then the copper ball and potion in the copper tank will be lost Soon, the cost will not be less than tin plating.

3. The copper in the hole is not guaranteed to contain all:

This problem will occur in every factory. As long as the tinning is poor, the positive film will still appear. The test will pass if there is copper on one side of the hole and the other side without copper. This has nothing to do with the positive and negative film. On the contrary, the negative film is easier to find. The reason is that the dry film is broken. When the board is etched, it is easy to enter the etching solution, and the copper in the hole will be easily etched. Poor tinning may be half of the tin is plated and the other half is not, then half of the copper and half are not. In addition, before the shipment of our board 100% all tested.

(5) Advantages of negative film:

1. No copper holes:

The hole does not need to be sealed with a dry film and directly etched can be 100% copper-free. On the contrary, it is not the same as a positive film. If the dry film has a small hole, it must be tinned. In this way, the copper in the hole cannot be etched off during etching. The batch factory will choose to drill twice, but the prototype will not be too long in the first time and the second cost is too high, even if the inspection is too strong, it is impossible to prevent missed inspections. I was in a factory because there were too many non-metallic holes. We did not use the second drill. We always missed the inspection. Customers always complained about the most serious accident. The high-voltage board was broken down because of the copper in the hole, and the losses were nearly 500,000. The problem was solved for one year, and all subsequent boards without copper holes were drilled twice.

2. Copper plating uniformity:

The copper plating of the whole board is better than the uniformity of the pattern plating. Because it is the whole board copper plating, the copper in the hole and the surface will be evenly plated than the pattern. The pattern plating is a sample plate because of the uneven pattern distribution. There are several types on the same hanging For the material number, he has to consider the pattern of each board to draw the current, so that some copper thickness may reach some.

3. The copper plating is only plated once, and the probability of copper delamination is low.

The positive film needs to be copper-plated twice. He knows that if there is oxidation and oil under the coating, the high-temperature copper layer is easy to separate. At present, we only do copper plating once for the negative film. You can think about the copper The greater the chance of tiering twice or the greater the probability of one.

4. We all know that Japanese boards are strict and demanding. Japanese boards and many Japanese circuit board manufacturers choose to use negative film production, indicating that this process is definitely no problem and is recognized. In addition, our factory has served tens of thousands of customers, and there is no quality problem caused by the negative film process.