Important PCB Checklist

Gone were the days where you need to wait for a few days before receiving a PCB quote from PCB suppliers and another couple of days to confirm a purchase order with them. With the fast development of internet technology, most PCB suppliers make full use of it and make online purchase much convenient  for customers. Currently, online PCB purchase can be done just within a few clicks. 

1.PCB CostMake sure the online ordering page offers you a complete quote, including an estimated shipping costs. Because you do not want to be surprised by any hidden costs when finally pay for your PCB online.

2.PCB Lead TimeDo not rush to click the purchase button. Make sure the PCB lead time matches your expectation. If you choose a shorter lead time while you don’t need, the cost may be higher.

3.Manufacturing FilesMost suppliers accept Gerber files, while some can manufacture your PCB from the design file itself. Depending on your preference, you should upload files accordingly before ordering the PCB online.

4.Layer Number

You need to make sure that the PCB layer you choose on the website fits your design. Most suppliers make double layers as default. If you need a multilayer PCB, different suppliers offers a different range of options for you.

5.PCB MaterialsMost suppliers have FR-4 as default because it is the most common PCB material. If your design requires other materials, be sure to contact the supplier before placing an order, or you can find alternative materials on the page to choose from.

6.PCB SizeSince various suppliers have different PCB manufacturing capability, if you are designing a fairly large PCB, you’d better contact with customer support team online. 

7.PCB Solder MaskThe default and cheapest solder mask color is green. Suppliers also can offer other color options, but these may be more expensive.

PCB Fabrication Materials

Although there is a wide variety available, all PCB fabrication materials are supposed to meet some standard criteria. The properties needed include high dielectric properties, low flammability in laminated plates, high conductivity for materials used on connecting components together etc. We will describe the most used PCB fabrication materials individually in the paragraphs below.

Copper-- is the metal used for conducting lines serving power and signal connections. Copper has a very high electrical conductivity and is relatively cheap.

Fiberglass-- is a fiber reinforced plastic used as an insulating material. It also had rigid property and is quite resistant to mechanical forces. There are standard thickness of fiberglass boards and standard types. Most types used are FR-2 and FR-4 which have better performance, but FR-2 is more expensive than FR-4. 

Gold-- is sometimes used to connect chip pins because of its good corrosion resistance performance.

Lacquer-like polymer-- is a polymer type used for soldering masks. The solder mask is a layer stretched across the entire PCB to prevent corrosion, external electric charge and dust. Different materials are added to the solder mask to get different colors, but mostly they are green.

Polyester-- is a naturally existed polymer in some plants. It is biodegradable and therefore eco-friendly. Polyester is used for printing silkscreen on the PCB board surface.

Polyimide-- is a polymer type used in flexible PCB boards. Polyimide is characterized with highly flexible, high dielectric properties, thermo-resistance, and is well-known for its unique orange color.

Solder alloy-- is a metal mixture of copper, tin, cadmium, silver, and other materials used to solder components on the board. It has a lower melting temperature than other materials it has contact with during soldering process. It has good electrical conductivity properties, close to those of copper and silver.

Except those materials mentioned above, there are dozens of other PCB manufacturing materials. The type of materials used depends on the quality you require, total product fabrication budget, and the environment in which the PCB will operate.

Considerations for High Frequency PCB Design

High-frequency PCB design requires a completely different set of knowledge compared to simple low-speed analog design or digital circuits design. Ignoring some of these practices may make the design be highly susceptible to EMI or cause signal loss. We here list some considerations for you when design a high frequency PCB.

1.Impedance MatchingImpedance matching is a key factor in high-frequency PCB design. As the frequency increases, the tolerance becomes lesser. Therefore, the designer needs to ensure that the impedance matches at the specified value.

2.Material SelectionUnlike low-speed or frequency designs, material selection is critical for a high-frequency PCB design. FR-4 here is not the best choice, because it can not achieve consistent dielectric constant of the PCB which is required by high-frequency design. This can lead to unacceptable signal losses in a high speed design.Instead, the ideal material for high-speed designs should have a much lower loss dissipation factor than the FR-4. In high-frequency design, even the slightest moisture of the PCB can affect the circuit itself. It is important to use a low moisture absorption material like PTFE.

3.Minimal SoldermaskYou may have chosen a suitable substrate for high-frequency design. But if you do not pay attention to the thickness of the solder mask, your design will still suffer from signal loss. Solder mask has a high moisture absorption rate, and wet solder mask is not suitable for high-frequency transmission.

4.Return LossReturn loss for a high-frequency design must be kept to the minimum. Since high-frequency signals use the least-inductive path, there should be no discontinuity in the ground plane below the signal traces themselves. Otherwise, high-frequency signals will use other non-ideal return paths, such as the power supply plane, and may cause ringing or reflections.

PCB Design Tips to Reduce Electromagnetic Interference Part2

PCB design becomes more difficult since electronic equipment have been more sensible and required excellent capability to reduce noise and electromagnetic interference. Thus, how to improve the design becomes one of the key issues that many engineers are concerned about. This article describes some tips for reducing noise and electromagnetic interference when designing PCB boards.

11.Single-sided board and double-sided board access to power and grounding by single point, thus power lines and ground lines should be as thick as possible.

12.Keep clock, bus wire and chip select signals far away from I/O lines and connectors.

13.Keep analog voltage input line and VREF away from the digital signal lines, especially the clock.

14.For A/D components, the digital part and the analog part should be unified rather than cross.

15.Both component’s pins and decoupling capacitor’s pins are as short as possible.

16.The key lines should be as thick as possible with protection on both sides, while high-speed lines should be short and straight.

17.Don't keep noise-sensitive lines parallel with high-current, high-speed switch lines.

18.Do not route below quartz crystals and noise sensitive components.

19.No current loop around weak signal circuit or low frequency circuit.

20.Do not form a signal loop, if inevitable, keep the loop area as small as possible.

21.One decoupling capacitor per integrated circuit. Add a small high-frequency bypass capacitor to the edge of each electrolytic capacitor.

22.Use high-capacity tantalum capacitors or poly condenser capacitors instead of electrolytic capacitors for charging and discharging storage capacitor. When using tubular capacitors, the housing should be grounded.

PCB Soldering Issues

PCB pads are easily peel off when the circuit board is being soldered or under repaired. In this article, some reasons for the falling off pads are analyzed, hope it is useful for your next project.

Reasons for easily falling off pads

1.Board quality issue. Due to the poor adhesion of the resin adhesive between the copper foil of the copper clad laminate and the epoxy resin, even the copper foil with a large area copper is slightly heated or mechanically stressed, it is very easy to separate with the epoxy resin which leads to the pad off, copper foil off and other issues.

2.Circuit boards' storage conditions.Affected by the weather or stored in the humid place for a long time, circuit boards absorb too much moisture. To achieve the desired soldering effect, SMD soldering needs to extend soldering time and temperature to compensate for the heat away due to moisture evaporation. Such soldering conditions easily separate copper foil and epoxy resin.

3.Problems caused by soldering irons.Generally, the adhesion capability of PCB boards can endure ordinary soldering process, which means no pad off phenomenon will happen However, electronic products generally needs repaired when running for a long time, repair by soldering iron is always the top choice. While the local high temperature of electric soldering iron can reach 300-400 degrees, and this made the temperature of pads up too high immediately, then resin will be off due to high temperature soldering, and pads will definitely be peel off.

Since pads are easily fall off, PCB manufacturers should take following steps to improve solder resistance to meet customers’ needs.

1.CCL suppliers should have good reputation for high-quality substrate they produced. Generally, copper clad fiberglass material selection and lamination process should ensure that the circuit board made of solder resistance will be in line with customer requirements.

2.Put desiccant and vacuum packaging the PCB board before shipping. Keep the circuit board always dry can reduce virtual welding and improve solderability. 

3.As to the effect about thermal shock caused by the soldering iron on pad, try to increase the thickness of the pad by plating copper foil. In this way, when the soldering iron heats the pad, the thermal conductivity of the copper pad is greatly enhanced, effectively reducing the local high temperature of the pad, and at the same time, the thermal conduction makes the pad detachable more easily and the soldering resistance of the pad is achieved.

Not to Touch PCB Boards by Hands

It is the common sense for PCB engineers that man can not touch the circuit boards directly by bare hands, but why? In this article, let’s find the reasons together.

1.The dangers of static electricity

Under different circumstances, electrostatic voltage carried by human body vary from several volts to hundreds volts to tens of thousands of volts. Touch electronic components directly by bare hands will generate electrostatic discharge, then devices are easily damaged and reliability are reduced; even worse, electrostatic discharge can make causes the device breakdown at once.

In addition, the electrostatic discharge process simultaneously radiates radio waves at a certain frequency and interferes with peripheral microprocessors, causing the application to run in disorder and seriously affecting the normal operation of the device.

Therefore, try to avoid direct human contact with electronic components in the daily work, especially in the charged state.

2.Effect by static electricity on the core board feedback loop

Human touch (the introduction of human equivalent resistance and other interference) can change the characteristic of feedback loop (including the pole offset), resulting in feedback loop oscillation and instable DC-DC output voltage.

Instable DC-DC output voltage can make the system restart (DC-DC automatically reduce the output voltage), even worse, it will burn out the main circuit board (DC-DC automatically adjusts the output voltage), thus the charged motherboard is not allowed to touch.

3.How to prevent the static electricity

a.anti-static cordless wrist band

According to the corona discharge effect and the principle of the tip discharge, when the accumulated charge exceeds a certain value, the potential difference is discharged to the space to achieve the purpose of eliminating static electricity. Static dissipative time: less than 0.5s; features: convenient, reliable.

b.anti-static wrist strap

Human skin contacts with the wrist strap made from the static conductive material directly, thus when the wrist strap grounding, discharge static electricity generated by human can be quickly discharged. Electrostatic discharge time is less than 0.1s.

c.anti-static PU coating gloves

Anti-static PU coating gloves can further prevent static electricity from being transmitted to printed circuit boards by hand contact. Hand back conductive wire spacing is 10mm.

4.Hardware protection

Electrostatic discharge immunity: air discharge ± 15KV, contact discharge ± 8KV;

Electrical fast transient burst: interference frequency is 5KHz or 100KHz, pulse group time 300 (1 ± 20%) ms;

Lightning (surge) immunity: 2KV capacitive coupling and gas discharge tube coupling, 1 time/min;

Conducted harassment immunity: 3V capacitive coupling and gas discharge tube coupling, test frequency is from 150KHz to 80MHz.

5.Software protection

The operating system is usually stored in Flash. Static interference of the Flash and unexpected power-off are prone to make the operating system lost and the file system damaged. Except the normal operation system, design a backup system in the normal flash storage area is necessary, thus when something wrong goes about the Flash, the backup system starts automatically to ensure that the product is still able to work stable.

Now you must understand why it is not allowed to touch the printed circuit board by hand, right?

2018 PCB Industry Forecast

PCB industry really did a good job in 2017, amazing data means a prosperous market in 2018. ITRI held a forecast for Taiwan's manufacturing industry, and once again revised up its output growth rate of manufacturing industry to 4.04% this year. It is expected that under the steady growth of the global economy, the growth of manufacturing industry next year will have an estimated annual increase of 3.25% and the output value can reach RMB18.15 trillion.

IEK predicted that next year the global economy was expected to continue this year’s growth trend. With the steady external demand and the gradual improvement of major electronic products like TV and smart phones, it was expected that China would have a sound manufacturing and sales performance. Manufacturing orders for semiconductors and machinery would be expected to inject momentum into manufacturing and sales growth momentum.

Although the global economy will grow steadily next year, the policy uncertainty of the major economies will increase the risk. The United States Federal Reserve will start to reduce its balance sheet plan, and monetary policy will enter into a double-stage tightening phase of raising interest rates and narrowing down the stocks. 

IEK suggested that the government should expedite the negotiation of the Taiwan-US economic cooperation agreement to help the industry deepen the connection with US end-customers and the supply chain. According to the statistics of the World Industry Association Database of the EU, the manufacturing industry in Taiwan and the United States has been developed fast in recent years and the U.S. industry demand has simultaneously led to the improvement of manufacturing industry in Taiwan province. 

Shih Hsin University professor Zhou Ji was invited to attend the meeting. He pointed out that according to the IEK data, the manufacturing rate maintained a high level. Among them, the peak of information electronic production capacity was up to 132%. 

No Right Angle Alignment in PCB Layout

Right-angle alignment is generally avoided in PCB wiring layout, and become one of the criteria to measure the quality of wiring layout. But do right angle-alignment influence the signal transmission?

In principle, right-angle alignment changes the width of the transmission line, resulting in discontinuities in impedance. In fact, not only the right-angle alignment, obtuse angle and acute angle alignment also can cause impedance changes.

The signal influence caused by right-angle alignment is mainly shown in three aspects: one is that the corners can be equivalent to capacitive loads on the transmission line which can slow the rising time; another is discontinuous impedance can cause signal reflections; the last is right-angle tip can generate electro magnetic interference.

The parasitic capacitance caused by the right angle of the transmission line can be calculated from the following formula: C=61W(Er)1/2/Z0. C refers to the corner’s equivalent capacitance (unit: pF), W refers to the trace width (unit: inch), εr refers to the dielectric constant of the medium, and Z0 is the characteristic impedance of the transmission line.

As the line width at right angles increases, the impedance there will be reduced, so there will definitely have a signal reflection phenomenon. We can calculate the equivalent impedance after the line width increases according to the impedance calculation formula of the transmission line. The reflection coefficient is then calculated according to the formula ρ=(Zs-Z0)/(Zs+Z0). Impedance changes due to the right-angle alignment are often between 7% -20%, so the maximum reflection coefficient is about 0.1. 

PCB Wave Soldering Process

Wave soldering is a batch soldering process used to make printed circuit boards. Wave soldering is used for through-hole printed circuit assembly and surface mounting.

In the process of wave soldering, the molten solder is transformed into the desired wave by mechanical bump or electromagnetic bump flowing that features jet flow. PCB board with assembled components must pass through the solder wave to allow mechanical and electrical soldering between component soldering points or PCB pad.

The main task is to pre-mold some components to make them meet the requirements of mounting, plugging and wave soldering.

The key steps in wave soldering process include component molding, component insertion or mounting, soldering and cooling by soldering waves. This means that molded components can be plugged on the PCB board as needed. Then PCB loaded with components is pushed into the wave soldering system by the transmission device. Next, solder flux is sprayed and PCB is preheated in the preheat zone. The final step comes with the wave soldering and cooling.

PCB Manufacturing Process

PCB manufacturing process contains a series of steps. This process requires advanced high-precision machines and is only cost-effective when daily PCB fabrication volume is large. 

The manufacturing process begins with specifying a PCB development software. The fully designed PCB is saved in Gerber format and converted into a film negative using a plotter. Place the film on a board made of plastic with copper layers on both sides. The film is placed on the copper layer and then radiated by UV light. The film layer is UV-sensitive in places where copper connection lines go through, but is UV-resistant in other parts, so the film in connection area can only adhere to the copper layer. 

The sequential process is an optical check of all plates for errors, and then layers are aligned on the same machine in the correct order. Fiberglass with glue is placed on each copper plate and plates are attached to each other in an aligned order. The entire board is heat-pressed by a mechanical control to bond the boards together with high precision.

After that is the process of drilling holes, copper is placed into the holes and the whole structure is cleaned up. The outer layers are prepared after finishing the inner layer process. To protect the copper in the outer layer from corrosion, a solder mask is applied and then cured under UV light, often, the surface color of PCB board is green. 

To make the process of components soldering easier, gold or silver is sometimes applied over the outer layer. Finally, the PCB board is cut, shaped, electrically tested, documented and packaged, thus the whole PCB manufacturing process is completed.

Tips for PCB DFM Problems

PCB design for manufacturing issues are very common during the whole board fabrication process. There are 5 tips for your reference in this article to avoid unnecessary issues in your next project.

1.Some pads on the PCB board are easy to peel off.

As shown in the picture below, the leftmost ground pad of this brush soldering pad is easy to peel off in the process of debugging or rear-end maintenance, which will make the entire board to be a scrapped PCB.

What cause this problem? We can easily see that the connection area between pad and ground is too large, so the heat conduction is very fast which cool the soldering process down very quickly, naturally it is easy to peel off when pulling.

Solution: a.Blind holes are drilled on similar pads to make them connect with adjacent layers and increase the pulling force on the board.b.Use teardrop alignment on similar brush soldering pads, the reason is the same as above.c.Fabricating narrow-middle window on such kind of pad, so that green oil on the pad will have a certain pull.

2.Ground pad shall be cross connected.

3.You'd better not drill holes on the button center. If you put on the button center, it won’t work for a long time because the center contact friction is relatively large.

4.Make sure the silkscreen on PCB board is clear and neat.

5.Generally, tin is used to painted on the metal positioning hole. To avoid assemble issue caused by tin, it is not recommended to expose copper on the back of metal positioning hole, if inevitable, just expose a little copper. 

How to Make a Printed Circuit Board

PCB fabrication capability becomes particularly important when dealing with high-frequency signals and weak signals which are two major difficulties in the field of microelectronics. So in this article, let’s discuss how to make a good PCB.

1.Clearly Design GoalsWhen receiving a new design task, clear the design goal is the first step. You need to make a standard board, a high-frequency board, small signal processing PCB, or a board with both high-frequency property and small signal processing?If it is an ordinary PCB, you only need to achieve reasonable layout and wiring, and ensure that mechanical dimensions can be exactly the same as per requirements. When there is a signal line over 40MHz on the board, you have to give careful consideration to these signal lines, such as crosstalk between lines and other issues.

2.Understand Requirements for Wiring LayoutDuring the wiring layout process, some special components will have special requirements, for example, analog signal amplifiers used for LOTI and APH require  a stable and small-ripple power.

3.Component Layout ConsiderationsThe first factor to be considered is the electrical performance, put components with close connection as nearer as possible. Especially for some high-speed lines, the layout should make it as short as possible, and the power signal and small signal devices should be separated.In the premise of achieving the circuit performance, you should consider the board’s mechanical size, the location of the socket, or if components’ placement is neat, beautiful, and easy to test, etc.

4.Wiring ConsiderationsWith the design conclusion of OTNI and star-shaped optical network, more boards with over 100MHz high-speed signal lines will need to be designed in the coming future. Any long signal path on a printed circuit board can be considered as a transmission line. If the transmission delay of the line is much shorter than the signal rise time, then the main reflection produced during the signal rise will be submerged. Overshooting, kickback and ringing no longer occur. For most current MOS circuits, the trace length can be measured in meters with no signal distortion since the rise time is much greater than the transmission delay. For integrated circuits, due to the faster edge speed, the length of the trace must be significantly shortened to preserve the signal integrity.

PCB Design Tips to Reduce Electromagnetic Interference

PCB design becomes more difficult since electronic equipment have been more sensible and required excellent capability to reduce noise and electromagnetic interference. Thus, how to improve the design becomes one of the key issues that many engineers are concerned about. This article describes some tips for reducing noise and electromagnetic interference when designing PCB boards.

1.High-speed chips are used in the key areas.

2.To reduce the upper and lower edge of the control circuit toggle rate, you can string a resistor.

3.Use the lowest frequency clock that meets system requirements.

4.The clock generator is as close as possible to the device using the clock. Quartz crystal oscillator housing shall be grounded.

5.Use the ground wire to enclose the clock area; the clock line should be short as far as possible.

6.I/O driver circuit should be as close to the board edge as possible. Signals should be filtered when entering the printed circuit board, so as signals from the high noise area. At the same time, it is necessary to use string termination resistor approach to reduce the signal reflection.

7.MCD unused end shall be connected to ground or defined as the output end.

8.Don’t keep the input end of gate circuit unconnected; positive input of unused op amp shall be grounded, while negative input should  be connected to the output end.

9.Printed circuit board should use the 45-degree fold line instead of the 90 one in order to reduce the launch and coupling of high-frequency signals.

10.Areas on printed circuit boards should be divided by the frequency and current characteristics of the switch; keep enough distance between noisy components and non-noisy components.

PCB Tinning

Printed circuit boards must be protected in several ways to ensure their effective performance. Since copper tends to be oxidized in the air, it is difficult to bond with solder and the conductive quality is lowered as the same time. Thus solder mask is widely used as a cheap way to cover untapped copper surfaces on PCB with the help of resins and paints.

PCB tinning is the process of applying a layer of tin on copper traces to prevent any possible degradation. Tin plating also helps to mask copper traces when the circuit board is etched. By doing this, the manufacturing process is simplified and unwanted etching is prevented thanks to the industrial process use highly concentrated solvents like sodium sulphate. 

PCB tinning is able to increase the current carrying capacity of traces for high-power rails. Choosing a thicker copper cladding for smaller high-current areas can make the circuit board more expensive. So PCB tinning is ideal for bridging high current paths. It is mainly done by concentrating the deposition with solder on a specific area.

PCB tinning process uses pure tin, or solder with a 60:40 mixture of lead and tin. 

There are many ways to tin a printed circuit board, but the most common one is to place the circuit board in a tin plating solution and introduce the tin electrode into a controlled current plating process. The second coating is done after the last fabrication step. 

The solder layer can be deposited either by hand or by a hot solder extruder that can deposit the solder blob on to the area. Tin itself will oxidize when exposed to the outside environment and therefore can not completely and reliably keep the printed circuit board unmasked, thereby applying a solder mask is necessary.

PCB Manufacturing Testing

Printed circuit board is the core of any electronic product, so testing them is crucial to during manufacturing process to ensure they can work efficiently as designed. There are several requirements for PCB production testing such as international regulation certification rest safety compliance test.

In general, PCBs are tested at every stage of their production to ensure the effective quality flow though the whole process. This test is a choice for small custom PCB designer who use PCBs for their own use. But on the other hand, large scale manufactures incorporate testing as an individual part into their manufacturing processes. Fabricated boards are initially visually inspected by qualified technicians who can find errors about imperfect surface finish or board design. Boards then undergo secondary check for further inspection preferably under a precision microscope to ensure the integrity of the design.

After the physical inspection, the board is electrically inspected to ensure accurate design flow down to the production line. The continuity of traces are tested separately by transmitting a low voltage signal and then using a high-resolution voltmeter to measure the voltage drop. In order to make the PCB manufacturing test easier, designers add test points particularly for testing the functionality. These points are usually small solder pads that power the board's basic functions, such as the main power rail and signal source.

Some PCB manufacturing test use custom test jigs to test the functionality of PCB board. Designers design a separate circuit board for testing the fabricated PCB. These test jigs are connected to the important ports of the PCB and power the board. The perfect alignment of various test leads on the PCB measures the signals of each part to ensure perfect function. This method makes the test more time-saving.

Skin Effect PCB Board

Although there are many factors that impede current flow in printed circuit boards, skin effect PCBs limit the flow of current by reducing the conductive area at high frequencies through passive resistance or unwanted inductances and capacitances.

At high frequencies, inductive inductance causes current to flow through the surface of the conductor rather than the entire conductor, which increases the resistance of the conductor. This effect is similar to any available resistive effect that prevents current flow, but it can increase as the frequency increases.

Skin effects also cause problems in high-speed links and data carriers. Due to frequent changes in current values, data lines may create unwanted passive components.

Since current flows evenly around the conductor, both sides of the conductor and ground line must be considered when making the calculation. Cause its effect only exists on high frequency circuits, so DC or low frequency system stands as an exception.

Since no compensation mechanism can be included at higher frequencies, the solution to solve skin effect is both space-consuming and simple.

For data carriers, the size of feed mechanism can be increased to reduce the resistance, but this can lead to some difficulties to PCB design.

This seems like a cliché, but it is the simplest solution to most problems. Determining the operating frequency and copper thickness and dielectric selection must be optimized to avoid such problems.

PCBA Introduction

PCBA is an abbreviation for printed circuit board assembly, refers to the combination of PCB, components and electronic accessories. Simply speaking, PCBA is actually a PCB with components assembled. This article make a brief introduction to PCBA, just for your reference.

PCBA Types

The main PCBA types are shown in the following picture.

So far, single-sided SMD and double-sided SMD are mainly used in the power board and communication backplane, other assembly types are used in complex devices like computers, cell phones, phones, etc.

SMT ProcessThe SMT process is a solder process where solder paste is pre-allocated to a PCB pad and melted through a reflow oven to achieve mechanical and electrical connection between the solder pads or pins of SMD and PCB pads. It is suitable for all types of SMD soldering. The main SMT steps contain tin paste printing, component mounting and reflow soldering.

Solder Paste Printing MachineThis is mainly composed of solder paste, model and paste printing machine. First of all, solder paste from the professional solder paste model through the solder paste printing machine should be printed on the corresponding position of printed circuit boards. Then electronic components are soldered by component mounting and reflow soldering.

Components Mounting MachineThis is mainly composed of SMDs, loader and mounter. The SMD is mounted on the certain position of PCB through component loader and professional installation software program and is soldered through reflow. There are two types of mounter, they are high-speed mounter and ordinary mounter. The former is suitable for the installation of crystal chips and small components, the latter is better for ICs, irregular and large components.

Reflow Soldering MachineThis is mainly composed of reflow oven. The SMD soldering is to make PCBs with components mounted on them pass reflow oven with soldering parameters set to implement components soldering. Reflow oven mainly contains infrared heating and hot wind heating.

Basics of PCB Soft Brazing

PCB soldering can be divided into the following three categories: fusion soldering, pressure soldering and brazing. Besides, there are other types of soldering like ultrasonic pressure soldering, gold ball bonding and laser soldering.

Brazing can be divided into hard brazing and soft brazing. The former refers to high-temperature large-scale soldering, the latter refers to lower-temperature small-size soldering like component soldering. The following is the supplementary to soft brazing.

Soft brazing refers to the soldering at temperatures below 450°C. That means the fusion point of soft brazing solder is lower than that of components, so components won't melt in the process of brazing, but soft brazing solder can be basically eliminated. This implies that soft brazing process is reversible.

When soldering metal, the soldered metal is heated to a certain temperature range, the activation of the soldering flux will be enough to remove oxide and pollutants on the metal surface. As solder occurs between solder and soldered metal surface, the solder will become solid after the solder joint is formed and cooled down. The extension strength is related to the lattice structure and thickness of the bonding layer between metals.

The main procedure of soft brazing contains wetting, diffusion, dissolution and metallurgic bonding.

Tips for Choosing Right PCB Prototyping Suppliers

Unlike building and selling mobile applications, launching electronics products to the market involves hardware and prototyping costs on top of professional services. Therefore, choosing a right PCB prototyping supplier do make sense. Engaging a wrong supplier can cause high development cost with little results to show. Here are some helpful tips for choosing a reliable PCB prototyping supplier.

Communication
There are thousands of PCB prototyping suppliers in Asian countries that can provide low cost and quick turnaround for your prototypes. Before start using any of them, make sure that they are able to communicate with you on the technical level because casual communication is pointless and time-waste.

Cost
Prototyping costs can break your budget. Please check the cost about prototypes, shipping and any additional taxes or duty imposed with your PCB prototyping supplier, ensuring that there are no hidden costs which will cause nasty feelings.

Lead Time
Electronic product development can be very competitive. It is the goal of many companies to enter into the market quickly without compromising product quality. Don’t trust those suppliers who promise to offer lower cost with fast turnaround. They often break their promise. At the very least, it is prudent to conduct a check on client’s review and feedbacks before cooperating with such suppliers.

Quality
Outsourcing the prototyping part of your design cycle does not mean you should address poor quality issue. On the contrary, getting PCB prototyping correctly manufactured and assembled can save unnecessary troubleshooting time.

Technical Knowledge
If you entrust your suppliers with design work and you focus only on completed prototypes, you need to ensure that they have a solid team of experienced engineers to turn your concepts into working prototypes.

Benefits of Using Heavy Copper PCBs

Currently, heavy copper PCB board is widely used in power supply systems and power electronics. The advancement of PCB technology has greatly improved the development of heavy copper printed circuit boards. Therefore, heavy copper PCB has a copper thickness of more than 6oz compared to the standard 2oz printed circuit board.

Why should we use heavy copper PCB? The reason is its extra copper thickness allows the PCB to conduct higher currents. In this case, such printed circuit board will have a good heat distribution making it easier to implement complex circuits in a limited space. Furthermore, compared to standard PCBs, heavy copper PCBs can increase mechanical strength so as to reduce circuit problems.

Heavy copper PCBs can be used in various applications, including automotive, new energy, military, heavy duty industrial equipment, etc. In addition, heavy copper circuit boards are really useful in departments that need to handle the heat generated by complex electronic circuits. Some specific industrial control modules also require heavy printed circuit boards to achieve effective heat distribution.

Bluetooth Circuit

Before analyzing the Bluetooth circuit in the module, we will briefly introduce the working principle of Bluetooth technology. Bluetooth is a communication protocol that operates within the 2.4GHz range. This radio-frequency range is similar to many other communication protocols like the very popular WiFi protocol.

The structure of Bluetooth communication contains a master device that can connect up to seven slave devices. Each slave communicates serially with the master, and communication between slaves can only be done through the master, which acts as an intermediary. Bluetooth devices can cover a range from 1 cm up to 100 meters. According to the range and energy consumption, Bluetooth devices are divided into three categories, the first category covers the maximum range.

Each Bluetooth device has the ability to maintain a low-power mode while idle, thus reducing energy consumption. For the communication between two Bluetooth devices, they need to exchange their unique code, so communication between them can only be done with user approval.

Multiple resistors are placed across the board as well as capacitors and diodes. There is a voltage regulator, a crystal-based clock, an antenna and two chips. The figure below shows the circuit final product after the assembly of the PCB board. This example is just one of many Bluetooth modules that exist in the transaction.

The general function is simple; the signal that gets from the aerial is dealt with in the chip, and then produce the output again. Depending on the purpose of your Bluetooth device, you can use a series of protocols called Bluetooth profiles to communicate between devices. For example, a serial communication UART is made using a serial port configuration file (SPP).

In order to make the module work properly, especially the assembly of the antenna, a high quality PCB assembly is required.

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Order From Best High Frequency PCB Supplier

You should take enough time to evaluate different HF PCB suppliers to ensure you can find the best. A reliable supplier will make timely use of your product, which will make it easy to resell to all your potential customers. If you plan to use them, you’d better evaluate different high frequency PCB products to determine if they work well in your product. Some tips you should consider for you to find a best HF supplier include the following:

Cost Different high-frequency PCB suppliers offer different prices. Compare product prices from different suppliers is necessary when determining your HF supplier. Suppliers who sell products online are best for your consideration because it is easy to compare online prices. If there are hidden charges, then you need to consider the charges carefully.

Management and Quality Control SystemThis is crucial to your design because a leading high-frequency PCB supplier can contribute to the quality performance and market reputation of your product. You need a factor-finding audit to them to make sure you have confidence with the supplier.

Technology CapabilityThis is one of the basic factors you should consider. If the supplier is able to match your technical requirements then you can get your design work and function properly. Otherwise, your time will be much wasted.

The Reputation of HF PCB SupplierYou can read comments and options from other customers before continuing to order. For example, reading reviews makes it easy to know if a given supplier can offer the top-quality product. Buy products from the supplier with good reputation will keep your project run smoothly. The supplier will avail the products in good time for you to continue with your operations.

Machine or Handmade Prototyping Boards

Whether starting from our own hobby projects or testing a new circuit concept, you'll be hovering between outsourcing PCB prototype boards or building your own board. Let's have a look at various aspects that may affect our choices.

Circuit ComplexityAre you building a simple timer circuit or a full-featured universal controller? A simple circuit may require the use of a prototype board as the cost of a prototype machine may not be justified. The same goes for complex circuits where signal integrity is really important. This is when machine prototyping is the wiser choice.

Component FootprintUsing a prototype board may limit your ability to use basic through-hole components. When using several surface mount components, you can still convert them to through-hole pins using a suitable adapter. However, if most of the components are SMD, or if footprints like QFN or BGA are involved, you would have no choice but to choose a machine prototyping board.

CostOf course, you want to save as much cost as possible in the prototyping phase. If you're building electronics just for fun, you might want to choose a low-cost prototyping method. Otherwise, time to market is more valuable than prototype cost, on behalf of a company, you may choose your prototyping board to be done by machine.

Turnaround TimeWhen a design becomes complex, it can take hours or days for manually soldering connections on a prototyping board. If anything goes wrong, any rework will delay days into weeks. If you are in a rush to develop a product development plan, you won’t want to waste any valuable types. Nowadays, various suppliers can deliver within days thanks to their leading manufacturing capabilities.

With today’s manufacturing capability, various suppliers are able to deliver within a couple of days. Ultimately, prototyping board which is done by hand or machine is best determined by your priorities and requirements.

Tips for Choosing A PCB Board Design Software

If you are serious working as an electronic designer, you may need to purchase a professional PCB design software instead of relying on a free one. The cost of professional software are different, but some most high-end software must definitely set you back for a fortune. Therefore, it is important to evaluate four aspects before making a purchase decision.

Accurate Design Rule CheckAny error in the PCB design software can be expensive because it means that no errors are detected on the prototype or finished board. Software suppliers have a good record and reference is very important. When you set up complex design rules, PCB design software must perform accurate checks.

Component LibraryAs more new electronic components are introduced, you will need a professional PCB design software with a comprehensive library. Therefore, it is unreasonable to spend countless hours to create footprints manually when you invest in a design software. At the very least, a qualified PCB design software should have a smart footprint generator tool.

Intelligent Routing FunctionOne critical reason why professional PCB design deserves its cost is to save you much time. A good design software allows complex tasks to be efficiently performed with the help of software intelligence. Functions like interactive or auto-routing are what you should look for in a good PCB design software.

Intuitive User InterfaceA paid professional PCB design software should be separate from the free version of their counterparts. The software's user interface should be graphical and intuitive to the designer. A PCB project can become much complex, thus you won’t want to spend valuable time learning how to organize your documents or bringing up measurement tools.

Before spending hundreds of dollars to buy a PCB board design software, you should carefully evaluate the above aspects among various vendors.