The first thing to note is that an ounce (OZ) is itself a unit of weight.

The conversion formula of ounce and gram (g) is: 1OZ ≈28.35g.

In the PCB industry, 1OZ means the thickness of copper that weighs 1OZ evenly spread over an area of 1 square foot (FT2).

It is the weight per unit area to express the average thickness of copper foil.

This is expressed by the formula, 1OZ=28.35g/ FT2 (FT2 is square feet, 1 square foot =0.09290304 square meters).

Specifically, the conversion method between it and length, also known as thickness, is as follows:

First, we know that the density constant of copper and the relevant unit conversion formula are as follows:

The density ρ of copper =8.9g/cm3

1 cm (cm) =10 mm (mm)

1 mm (mm) =1000 micron (um)

1 mil material 25.4 um

1 FT2≈929.0304cm2

1 mil material 25.4 um

According to the mass calculation formula m = ρ×V (volume) = ρ×S (area) ×t (thickness), know the weight of copper foil divided by the density and area of copper foil thickness!

As previously known, 1OZ=t×929.0304cm2×8.9g/ cm3=28.35g

Therefore, t=28.35÷929.0304÷8.9cm≈0.0034287cm=34.287um≈34.287÷25.4mil≈1.35mil

The thickness of 1OZ copper foil is 35um or 1.35mil.

Copper thickness 1.OZ(0.035mm) Copper thickness 1.5OZ(0.05mm) Copper thickness 2.OZ(0.07mm)

First, we don't want to die copper (island), because the island here forms an antenna effect, if the radiation intensity of the surrounding line is high, it will enhance the radiation intensity of the surrounding; And will form the antenna acceptance effect, will introduce electromagnetic interference to the surrounding lines.

Second, we can delete some small islands. If we wish to retain the copper cladding, the island should be well connected to GND through the ground hole to form a shield.

Third, at high frequencies, the distributed capacitance of the wiring on the printed circuit board will come into play, and when the length is greater than 1/20 of the wavelength corresponding to the noise frequency, an antenna effect will occur and noise will be emitted outward through the wiring. If there is a poorly grounded copper-covering line in the PCB, the copper-covering becomes a noise transmission tool.

Therefore, in the high frequency circuit, do not think that the ground ground somewhere, this is the "ground wire", must be less than λ/20 spacing, in the wiring through the hole, and the ground plane of the multilayer "good grounding". If the copper coating is properly treated, the copper coating not only increases the current, but also plays the dual role of shielding interference.

Fourthly, by punching the ground hole and retaining the copper covering of the island, it can not only play the role of shielding interference, but also prevent PCB deformation. Source network

The Via hole plays the role of connecting the lines to each other. The development of the electronics industry also promotes the development of PCB, which also puts forward higher requirements for the production process and surface mounting technology of printed board. Via hole plugging technology comes into being and should meet the following requirements:

(1) There is copper in the through hole, and welding resistance can be plugged or not plugged;

(two) there must be tin lead in the through hole, there is a certain thickness requirement (4 microns), no solder resistance ink into the hole, resulting in tin beads in the hole;

(three) the pass-through hole must have solder resistance ink plug hole, light proof, no tin ring, tin beads and flat requirements.

With the development of electronic products to the direction of "light, thin, short, small", PCB also to high density, high difficulty development, so there are a large number of SMT, BGA PCB, and customers require plug holes when pasting components, mainly has five functions:

(a) To prevent PCB over wave soldering tin through the through hole through the component surface resulting in short circuit; In particular, when we put the hole on the BGA pad, we must first do the plug hole, and then gold-plated treatment, to facilitate the welding of BGA.

(2) To avoid flux residue in the pass-through hole;

(3) After the completion of surface mounting and component assembly in the electronics factory, the PCB should be vacuated on the testing machine to form negative pressure:

(four) prevent the surface solder paste into the hole caused by virtual welding, affecting the installation;

(5) To prevent over wave soldering tin bead pop out, resulting in short circuit.

The realization of conductive hole plugging process

For the surface mounting plate, especially the mounting of BGA and IC, the requirements for the through-hole plug hole must be flat, convex and concave plus or minus 1mil, and the edge of the through-hole shall not be red and tinned; Through the hole hidden tin beads, in order to meet customer requirements, through the hole plugging process is all over the place, the process is particularly long, process control is difficult, often in hot air leveling and green oil soldering resistance experiment oil loss; Problems such as oil explosion occur after curing. Now according to the actual conditions of production, the PCB plug process is summarized, in the process and advantages and disadvantages of some comparison and elaboration:

Note: The working principle of hot air smoothing is to use hot air to remove excess solder on the surface of the printed circuit board and inside the hole, and the remaining solder is uniformly covered on the welding plate and the line and surface seal decoration of the open solder, which is one of the surface treatment methods of the printed circuit board.

First, hot air leveling after plugging process

The process flow is: plate welding resistance →HAL→ plug → curing. Non-plug hole process is used for production. After hot air leveling, aluminum sheet screen or ink screen is used to complete the through-hole plug holes of all strongholds required by customers. Plug hole ink can be photosensitive ink or thermosetting ink, in order to ensure that the wet film color is consistent, plug hole ink is best used with the same ink. This process can ensure that the hot air leveling through the hole does not drop oil, but easy to cause plug hole ink pollution, uneven surface. It is easy for customers to cause virtual welding when mounting (especially in BGA). So many customers don't accept this approach.

Two, hot air leveling before plugging process

2.1 Pattern transfer is carried out with aluminum sheet after plugging, curing and grinding

This process uses a CNC drilling machine to drill out the aluminum sheet to plug holes, make a screen version, plug holes, to ensure that the through hole plug hole full, plug hole ink, plug hole ink can also be used thermosetting ink, its characteristics must be high hardness, small resin shrinkage change, and hole wall binding force. The process flow is as follows: pretreatment → plug → grinding → pattern transfer → etching → plate resistance welding

This method can ensure that the plug hole of the conduction hole is smooth, and there will be no quality problems such as oil explosion and hole edge oil in hot air leveling. However, this process requires one-time thickening of copper, so that the copper thickness of the hole wall can meet the customer's standard. Therefore, it has high requirements on the copper plating of the whole plate and the performance of the grinding machine, so as to ensure that the resin on the copper surface is completely removed, and the copper surface is clean and not polluted. Many PCB factories do not have one-time copper thickening process, and the performance of the equipment can not meet the requirements, resulting in this process is not used much in PCB factories.

2.2 Solder the screen face directly after plugging the aluminum sheet

This process uses a CNC drilling machine to drill out the aluminum sheet to plug holes, made of screen plate, installed on the screen printing machine to plug holes, stop for no more than 30 minutes after the completion of the plug hole, with 36T screen directly screen face welding, the process is: pre-treatment - plug hole - screen printing - pre-drying - exposure - development - curing

This process can ensure that the oil cover through the hole is good, the plug hole is smooth, the wet film color is consistent, the hot air leveling can ensure that the through hole is not tin, no tin beads in the hole, but it is easy to cause the ink pad in the hole after curing, resulting in poor weldability; After hot air leveling, oil bubbles off the edge of the through hole. It is difficult to use this process to control the production, so process engineers must adopt special flow and parameters to ensure the quality of the plug hole.

2.3 Aluminum sheet plug hole, development, precuring, grinding plate after the plate face welding

With CNC drilling machine, drill out the requirements of the plug hole aluminum sheet, made of screen plate, installed in the shift screen printing machine for plugging holes, plug holes must be full, both sides prominent is better, after curing, grinding plate surface treatment, its process is: pre-treatment - plug hole a pre-drying - development - pre-curing - plate surface welding

Because this process uses plug curing to ensure that HAL through the hole without oil, oil explosion, but HAL, through the hole hiding tin beads and through the hole tin is difficult to completely solve, so many customers do not accept.

2.4 Plate welding and plug holes shall be completed at the same time

This method adopts 36T (43T) silk screen, mounted on the screen printing machine, using a plate or nail bed, while completing the board surface, all the pilot holes are plugged, the process is as follows: pre-treatment - screen printing - pre-drying - exposure - development - curing.

This process time is short, the equipment utilization rate is high, can ensure that the hot air leveling through the hole does not drop oil, the through hole does not tin, but because of the use of silk screen to plug holes, there is a lot of air in the through hole, during curing, air expansion, break through the welding resistance film, resulting in holes, uneven, hot air leveling will have a small amount of tin through the hole.

When designing PCBS, we often rely on previous experience and tips found on the Internet. Some rules are universal at design time, while others are limited to specific designs.

For example, ADC PCB rules do not apply to RF and vice versa. However, certain guidelines can be considered universal for any PCB design. Today to Kangkang some can significantly improve the PCB design of the basic problems and techniques.

1. Power supply and signal distribution

Distribution is a key element in any electrical design. All components rely on strength to perform their functions. Depending on your design, some components may have power connections, and some components on the same board may have poor power connections.

For example, if all components are powered by a single wire, different impedances will be observed for each component, resulting in multiple ground references. For example, if you have two ADC circuits, one at the beginning and one at the end, and both ADCs read an external voltage, each analog circuit will read a different potential relative to themselves.

We can summarize the power distribution in three possible ways: single point source, star source, and multiple point source.

(a) Single point power supply:

The power and ground wires of each component are separated from each other, and the power lines of all components meet only at a single reference point, which is considered to be suitable for power. However, this is not feasible for complex or large/medium projects.

Since the mention of Industry 4.0, China's traditional manufacturing has gradually changed into intelligent manufacturing. The combination of manufacturing and information technology is a breakthrough in China's industrial history. Therefore, PCB online pricing system can be said to be the product of The Times, it breaks the traditional factory off-line quotation mode, greatly improve the factory production efficiency.

However, many people are confused by the variable price of the online quotation system. The following is an example of the online pricing system independently developed by hunting Board to say the reasons for the variable price.

1. The selection of plate type affects the price

PCB industrial chain from upstream raw materials to midstream base materials, each link will have an impact on PCB quotation, and the cost of raw materials accounts for the largest proportion of PCB operating costs, about 60-70%.

PCB manufacturers on the market to provide a variety of boards are different, the price is not the same. Manufacturers provide too many plate types, shoddy, uneven phenomenon is not easy to distinguish. Therefore, we provide Kingboard FR-4 and CIM-1 which can basically meet all product requirements. Compared with CIM-1, the FR-4 has a wide range of adaptation and high performance, and therefore a higher price.

2. Different production processes lead to price diversity

Different production processes result in different costs. Take the hunting board pricing system as an example, the price difference between the gold plate and the bare copper plate is 90 yuan, the tin spray, OSP structure are also different, in addition to the surface treatment, plate thickness, copper thickness, whether the plate and other processes will form different costs, resulting in the diversity of prices.

3. Different production difficulties affect the price

Process difficulty is the main factor affecting pricing, the price of six-layer board, eight-layer board is several times or even dozens of times of single and double panel. The complex process of multilayer board and high scrap rate result in high cost.

At the same time, the difficulty level of PCB itself will also cause different costs. For example, there are 500 holes on two PCBS, with one aperture larger than 0.3mm and the other aperture smaller than 0.3mm, different drilling costs will be formed. The same principle holds for line width and line distance, which will also cause different production costs. Difficult PCB scrap rate is high, the cost is bound to increase, and then affect the price.

4. Special technology affects the price

At present, in the PCB industry, there are not many manufacturers that can do special processes. Some special processes such as large size board, resin plug hole, impedance control, plate edge coating copper, square groove, etc., may need to introduce a batch of special equipment to meet the production conditions, increasing the equipment cost; At the same time, due to the particularity of the process, it also increases the manufacturing cost.

The above basically includes several factors affecting PCB quotation. To be specific, in addition to raw material cost, process difficulty and other factors, different regions will also affect the freight price. Customer special requirements, such as solder color, reporting requirements, shipping requirements, etc., will also affect the final offer to a lesser extent.

The cost calculation of PCB industry is the most special and complex in all electronic industries. The online pricing system perfectly solves the disadvantages of traditional quotation, and also reflects the intelligent level of a PCB factory. The online pricing system independently developed by Hunting Board is simple to operate, price transparent, convenient to check price details, and very friendly to new users.

Since its birth, 5G technology has always been a topic of close attention. Since the beginning of the 20th century, 5G has become popular and the Internet of Everything era has arrived, which is undoubtedly a new opportunity for all walks of life, especially for the electronics industry, which is a crucial development opportunity.

The development of 5G promotes the construction of large-scale data centers, which means that a large number of high-end PCB communication boards will be needed to support the huge traffic carried by data center servers, so the requirements for the number of layers and materials of PCB multi-layer circuit boards will be increasingly high. There is no doubt that the development of 5G drives PCB multilayer board to the direction of high precision and more complex.

PCB multilayer board is the general name of more than two layers of circuit board, composed of several layers of insulating substrate on the connecting wire and assembly welding electronic components of the welding plate, not only has the conduction of each layer of lines, but also has the role of mutual insulation. They are much more difficult to process than single and double panels and require higher quality and reliability. They are mainly used in communication equipment, high-end servers, medical electronics, aviation, industrial control, military and other fields.

From different angles, the influence of 5G on PCB multilayer board is as follows:

1. From the perspective of the construction of a single base station, due to the characteristics of 5G with high frequency and high speed, the value of the communication circuit board will be greatly improved, and the added value of the multilayer board will be increased.

2. From the perspective of the number of 5G base stations, the number of 5G base stations will be much more than that of 4G base stations, especially a certain number of micro base stations will be covered in the blind spot area, and the demand for circuit boards will be more.

3. From the perspective of 5G technology, the increase of 5G channels will lead to higher requirements for the area and number of layers of single PCB multilayer board, higher requirements for the performance of the board, and higher production costs.

The size of terminal equipment is decreasing to meet the needs of users for portability, but board level functions are becoming more and more complex, and more and more high-speed signal applications, resulting in more and more crowded PCB space, the above electronic products in multiple development directions need PCB miniaturization. Methods for reducing PCB size, or improving PCB "integration," are generally broken down into three categories: increasing the number of layers, reducing the line width, line spacing and aperture diameter, and using new materials.

PCBS (printed circuit boards) have become the dominant industry in Asia Pacific, especially by Chinese companies.

According to the IPC, Greater China accounted for 63.6% of the global PCB production capacity in 2017 (of which the mainland accounted for 52.7%). If Korea and Japan are included, East Asia accounts for more than 80% of the global PCB production capacity.

PCB in Europe and the United States has gradually become a sunset industry, the overall trend of decline, but there is a PCB company headquartered in the United States has been concentrating on the PCB industry in recent years, and the momentum is good, not only in terms of sales in the world's third largest, but also in 2018 growth of more than 10%, sales of more than 2.8 billion dollars, and in the electronics industry is expected to be pessimistic when said, The company still expects to achieve positive growth in 2019.

A PCB manufacturer from the United States

The company is U.S.-based TTM Technologies. At the 2019 International Intelligent Manufacturing Eco-Chain Summit, Tom Edman, CEO of Schindler Technology, delivered a keynote speech, and accepted an exclusive interview with TechSugar after the meeting, telling readers about his understanding of the PCB industry.

We note that Qualcomm is in the process of applying for a license to supply Huawei to the United States, and Huawei is willing to use Qualcomm chips to manufacture phones if the U.S. government allows it." Perhaps for some people, it is difficult to accept the use of Qualcomm Snapdragon chips for domestic Guanghua mobile phones. After all, the core reason why Huawei mobile phones make some people proud is the use of self-developed Hesis chips. But at this juncture, for the current Huawei: "Huawei is now facing great difficulties. Continued pressure, to our business has brought a lot of pressure, survival is our main line." "Guo Ping said.

Why is Huawei using chips from US company Qualcomm?

In the 5G era, there are only a handful of companies capable of designing 5G mobile phone chips: Qualcomm (US), Hesse (Mainland China), Samsung (South Korea), Mediatek (Taiwan China) and Unigroup Zhanrui (mainland China). Among them, only Samsung has the capability of both chip design and chip manufacturing. The rest are pure chip design manufacturers who need to rely on chip foundries like Taiwan Semiconductor Manufacturing to produce designed chips. In addition to the chip design must use the American EDA design software (at present, the world's three major EDA companies Synopsys, cadence? And? mentor? Graphics has 80% of the market. All three companies are U.S. companies or U.S. incorporated companies), but they also have a lot of U.S. equipment involved in chip production. Applied Materials of the United States and Pan Forest Semiconductor of the United States have a large market share in semiconductor equipment.

According to the ban of the US Department of Commerce on Huawei, any company in any country that contains US technology must cut off supply to Huawei unless approved by the US Department of Commerce. Therefore, both Qualcomm Mediatek Unigolor, which only has design capability, and Samsung, which also has chip manufacturing capability, do not have chip design and manufacturing capability that "does not include US technology". Had to stop supplying Huawei until the U.S. Department of Commerce approved it. Of course, as a profit-oriented company, no mobile phone chip company would not want to make a lot of money at the same time as Huawei is unable to produce its own Kirin core.

Huawei sold more than 240 million smartphones in 2019. In the current mobile chip market, according to the latest data, Qualcomm and Mediatek's share of the bite is very dead. In the third quarter of 2020, Qualcomm shipped 130 million mobile chips, while Mediatek was about the same. In other words, Huawei will sell almost as many phones in 2019 as Qualcomm or Mediatek sell chips in half a year, even if global sales are hindered. Therefore, for the mobile phone chip market, whoever can win Huawei's order can establish the industry leader position at one stroke, and the latter is hard to overtake. In this context, Qualcomm and Mediatek will inevitably apply to the US Department of Commerce to supply Huawei. But at the current pace, only two companies have received approval from the US Department of Commerce to resume supplying Huawei since the ban went into effect on September 15: Intel and AMD. This is equivalent to the fact that Huawei's PC or server products can continue to be produced on the premise of using American chips.

So the US is not really trying to kill Huawei, but to keep it a place down the chain of core technologies it controls. So while it would be a hundred times better for Huawei to choose either Mediatek or Samsung (Unigolor currently only makes low-end chips) than to simply cut off its own supply from Qualcomm, the fact is that if the US Department of Commerce approves a company to supply Huawei with chips for its phones, Qualcomm is likely to be the only candidate. Moreover, Huawei should have foreseen that it might have to work with Qualcomm on its phone chips. In my previous article, why does Huawei pay royalties to Qualcomm in the 5G era? As I've written before, on July 29, Qualcomm signed a long-term patent licensing agreement with Huawei that gives Huawei access to Qualcomm's patented technology in exchange for $150 million per quarter.

The agreement puts an end to a long-running patent dispute between Huawei and Qualcomm, and will allow the two companies to talk a lot more about chips once they get along. For Huawei, on the one hand, the performance of Qualcomm chips is absolutely no problem. After all, the majority of domestic 5G phones are using Qualcomm's Snapdragon series chips. On the other hand, according to Huawei's 2019 financial report, its consumer business has accounted for 54.4% of its annual revenue, and the majority of the consumer business is the mobile phone business. If Huawei used to be a communications equipment company, now it is more like a mobile phone company.

Therefore, letting Huawei give up the mobile phone business because of the chip problem is tantamount to letting Huawei cut the most important link in its mature 5G industrial chain product line, giving away its 40% share of the domestic mobile phone market. Moreover, Huawei's current product strategy is called "1+8+N", in which "1" is smart phone. It can be said that in Huawei's consumer business strategy, 1, namely mobile phone, is the whole fulcrum.

If Qualcomm chips can be used, Huawei can at least keep the most strategic and profitable mobile phone business, keep the large number of jobs in the mobile phone business, keep the brand of Huawei mobile phone, and keep the HMS ecosystem of Huawei. At the same time, the money earned from the mobile phone business can be continuously invested in basic scientific research. Therefore, Huawei's purchase of Qualcomm's chips is a "win-win" choice in the current era. It not only makes Qualcomm a lot of money, but also gives Huawei the capital to accumulate courage and endure hardships. After all, only when there is green hill can there be no fear of firewood