Archive for the ‘Our News’ Category

The function of solder mask layer on the PCB Board.

Monday, September 20th, 2021

At last time, we shared a blog talking about Why most of the PCB boards are green? . Believe you’ve known the reasons for why most of solder mask colors are green.

Today, let’s share something about the function of solder mask on the Printed Circuits Boards.

The solder mask layer is designed mainly to prevent the PCB copper foil from being directly exposed to the air and play a role in protecting the PCB surface, which is also to prevent the area that should not be soldered from being soldered.

PCB Solder mask

As we know that almost all the PCB need to do the assembly, which need to go through the reflow soldering while the assembly, and solder mask plays an important role during control of the reflow soldering process.

Here is a summary for what solder mask roles played on the board:

(1) Prevent physical disconnection of conductor circuits on the circuits board;

(2) In the welding process, solder mask can prevent short circuit caused by bridging;

(3) solder mask can reduce copper pollution to the soldering trough;

(4) Print solder mask on the PCB can prevent insulation deterioration and corrosion caused by external environmental factors such as dust and moisture;

(5) Solder mask are with high insulation; it is possible to increase the density of the circuit.

Red solder mask

In terms of solder mask material, it must be used through liquid wet process or dry film lamination.

Dry film solder mask materials are supplied in a thickness of 0.07-0.1mm (0.03-0.04″), which can be suitable for some surface mount products, but this material is not suitable for PCBs with tighter pitches.

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Baking Time & Temperature Standard of MCPCB

Tuesday, August 17th, 2021

After manufacturing the Metal Core PCB, there is a shelf life, once the shelf life has passed, we need to bake the bare board before assembling the components, otherwise the MCPCB is prone to burst when the SMT line is produced. There are industry specifications for both how long MCPCB can be stored and how long they can be baked.

MCPCB Control Standard

  1. Unpacking & Storage
  2. If the packing bag is sealed, and the manufacturing date is within 2 months, it can be directly used before assembly.
  3. The manufacturing date is within 2 months, and the unpacking date must be marked after unpacking.
  4. The manufacturing date is within 2 months, and it must be assembled and used within 5 days after unpacking.
  • Baking Time
  • If unpacked for more than 5 days within 2 months of the manufacturing date, bake at 120±5°C for 1 hour
  • Two months after the manufacturing date, baking at 120±5℃ for 1 hour before assembly.
  • Two to Six months after the manufacturing date, baking at 120±5℃ for 2 hours before assembly.
  • Six to Twelve months after the manufacturing date, baking at 120±5℃ for 4 hours before assembly.
  • The MCPCB after baking must be used up within 5 days (put into IR REFLOW), and unused board must be baked for another hour before assembly.
  • Over half one year after the manufacturing date, bake at 120±5℃ for 4 hours before assembly, and then send it to the production line to do HASL_LF before using.
Baking Machine

Preservation & Baking Standard for in different regions

The specific storage time and baking temperature of MCPCB are not only related to the production capacity and production process of manufacturer, but also have a great relationship with the region.

  1. For areas with heavier humidity, the MCPCB must be used up within 24 hours when exposed to the air, otherwise it is easy to oxidize. After normal opening, it is best to use it up in 8 hours.
  • For areas with a relatively dry climate, the preservation time of PCB will be longer, and the baking time can also be shorter. The baking temperature is generally 120±5℃, and the baking time is determined according to the specific situation.

The MCPCB with OSP or Gold Immersion has a shelf life of 6 months after packaging, and it is generally not recommended to bake for MCPCB with OSP.

PCB board with SMT

If you have other questions about MCPCB, welcome to contact us.

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What kind of test for Coil Printed Circuit Board?

Wednesday, August 11th, 2021

In year 2019, one of our US customers asked us, Marina can Best Technology make a Coil PCB (Printed Circuit Board) with FR4 material? Yes, of course, we can make different kinds of PCB for our customer, included for the Coils PCB, which currently is widely used for wireless charging and antenna products. Please see the following Coils board from Best Technology.

The manufacturing process is same as other PCB manufacturing process, and just make sure the etching process and pay attention for the etching tolerance of the coils trace. And when coils PCB board finished, do you know what kind of test need to do to check the functional of Coils boards?

Today I would like to share how Best Technology test Coil PCB board. Everyone knows that we check the quality of PCB board with Flying probe tester, as the production efficiency is extremely low and the inductance and capacitance cannot be accurately measured. In this way, we need to use LCR meter to make verify the inductance and capacitance. See the LCT meter as following.

Best Technology chooses the digital meter LCR Meter to test the impedance characteristics of the coil. From the LCR tester you know see two numbers, one for inductance and another for resistance.

After test each coils printed circuit board, we will make record at our paper to make sure every measurement data will meet for customer requirement.

Currently, LCR Meter only provides a single-channel test function, and can only test the impedance characteristics of a set of coils at a time. But this is the effective test method for Coil printed Circuit Board. But we believe we will buy more LCR meters to let the test coil board become quicker.

If you have any comments on the testing for Coil printed circuit board, you are welcome to send us query and we are happy to discuss with you. You can visit www.bestpcbs.com to know more about us. Thank you

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The way to add the mouse bite on the PCB Panel #Bestpcb

Saturday, July 31st, 2021

#Bestpcb #Best PCB

Maybe you’ve ever been recommended by your PCB manufacturer to add a mouse bite on the PCB edge

But, what’s mouse bites?  Is it something about the Rat?

Of course not, it is kind of connection way for PCB Panel.

As you know, usually the Printed Circuits Boards are manufactured on a standard sized panel, and sometime, the panel will with sharp edges, and those sharp edges are often referred to as “mouse bites” and they are left over after depanelization.

mouse bite PCB depanelization Best Technology

Mouse Bites usually presented as row of tiny holes on the board edge, just like the half holes around a stamp, which to connect and allow those small boards in an array.

mouse bite stamp holes on the PCB edge

Here is the picture for you to see how the mouse bites presented on the Gerber drawing and what it is when it is finished.

Partial Effect drawing after Penalization: (the way of connecting bridge is used in the middle, this way can reduce the residue of burr in minimize)

Partial Effect drawing pcb panel
PCB panel mouse bite

Some People also called mouse bites as perforated breakaway tabs, it is designed for a better the purpose of the mouse bites is for a better grasp when mounted.

Here is the design rules if you need to add the mouse bites on your PCB panel.

  1. The distance between each single board need to arranged as 1.2mm and 1.6mm.
  • The distance between each holes need to be 0.2mm, the distance between holes center should be 0.75mm.
  • Need to add two rows, the mouse bites extend to 1/3 of the board, if there is a some circuits on the board edge, you will need to avoid it.
  • After adding mouse bites, the shapes of the two sides of the hole are connected, which is convenient for the production of gongs after work.

Here are some of our PCB with mouse bites for your reference.

mouse bite PCB Best Technology
PCB with mouse bit

If you want to add mouse bites on your PCB board, you are welcome to send us your request and we will help you make it on your PCB Panel.

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How to make Panel for MCPCB?

Friday, July 16th, 2021

Regarding all Metal core PCB required panelization, which needs to take into account how the boards are connected. There are two main connection methods for panel: Double face carved V-shaped groove (V-CUT), and the long slot plus a small circular hole (commonly known as stamp hole), depending on the shape of the PCB.

  1. V-CUT

V-CUT is to draw a slot at the junction of two boards, where the connection of the boards is relatively thin and easy to break. Currently SMT Board is widely used, characterized with neat and level edges after separation, which is recommended as priority.

V-cuts are generally straight lines, and there will be no complicated traces such as curved arcs, so pay attention to be in a straight line when making the panelization. Please also note the following two points.

① The two sides of V-CUT line (top side and bottom side) require a no circuits area that is not smaller than 1mm, to avoid the damage circuits when separating.

② After cutting the V-shaped groove, the remaining thickness should be 1/4 to 1/3 of the total board thickness , which is not smaller than 0.4mm.

V-Cut
  • Stamp Holes/Mouse Bite

For irregular PCB boards, the shape of the board has curved corners, there will be many burrs if use V-cut. In this case the stamp hole connection would be the better choice.

  1. Panelization Rules:
  1. The spacing between the panel and the board is 1.2mm or 1.6mm.
  • The diameter of hole is 0.55mm, generally a row of 8 holes (Hole count depends on the design requirements, more holes can enhance the stability), the spacing of the two holes is 0.2mm.
  • The distance between the upper and lower rows of holes is 2mm, and 1/3 of the stamp holes enter the board. Pay attention to avoid the circuit on the edge of the board.
  • After adding the stamp holes, the shape of both sides of the hole need to be connected to facilitate the subsequent routing manufacturing.
  • The part picture after panelization.(Using the connection bridge in the middle, which can minimize the residual.)
Part Picture
  • The effect picture after panelization.
Stamp Holes

If you want to learn more about MCPCB design, welcome contact us.

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What is flying probe test printed circuit boards?

Wednesday, June 16th, 2021

Before leaving PCB manufacturing line, bare PCBs (Printed Circuit Boards) have to pass electrical tests so that it guarantee that boards go for high performance and high reliability after finish the SMTSurface Mount Technology. Electrical tests are implemented to find out electrical and circuitry issues such as shorts, opens, resistance, capacitance etc. all of which indicate whether bare boards or assembled board are correctly fabricated.

shorts circuit

When test probes work, it moves quickly from test points to other test points as per instructions instructed by the computer set up program.  

probe flying test

Probe test is no need fixture, so it is very popular in the printed circuit boards manufacturing. The most significant reason is their cost. it is highly cost-effective for prototypes and low to mid-volume production. And the most important factor, the test reports can be provided for each board after finish tested and it is very easy to export from the computer, you can send to your customer very quickly for the test results of PCB.

Advantages of Flying Probe Test:

Low test cost (Eliminates fixturing costs and time)

Short test development time

Fast computer program development, easy integration of design changes

Rapid feedback provided to PCB design engineers at prototyping period

Process flexibility

Circuit access, even in the absence of test points

Controlled probe contact, programmable for any type of board

Different test solutions and approaches integrated in a single test system

Intrinsic positioning and measurement precision

Disadvantages of Flying Probe Test

Everything has two sides. Apart from obvious advantages, flying probe test have some disadvantages.

Since flying probes have direct physical contact with vias and test pads and small pits are easily caused on board surface, when flying probe tester is working on components without test pad, it’s possible that probes have contact with component leads so that loose leads or leads with badly-performed soldering may be missed.

In spite of the disadvantages mentioned, flying probe test is still regarded as a significant test method for PCB fabrication. Flying Probes have enhanced the competitive variable as lost time due to retooling has been removed. Prototype and Quick Turn product is the perfect match for Flying Probes as they carry out in low quantity orders and are quick to change jobs, unlike the long setup times with fixture testers.

By the way, to test circuit shorts, opens, Best Technology also do AOI checking to make sure there is no issue for PCB manufacturing.

AOI test

Contact Best Technology right now, to discuss more for printed circuit boards.

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How to do SMT for ceramic PCB

Wednesday, May 19th, 2021

As we all know if ceramic PCB is very fragile, so it is not easy to do SMT for them.

But we can do the SMT for ceramic PCB easily because we do it every day and we have more than 15 years experiences for doing that.

For the almost SMD components (such as SMD rsistors, capacitors, diode etc), normally we will add the solder paste by using SMT stencil, then put the components by machine, finally do the oven reflow.

For some special components, we will need to solder it by hand, such as through connectors, but it can’t be soldered by hand directly, it need to be put on the heating table to keep the temperature is high enough to make the solder past at melt state. Because the ceramic material with very good heat dissipation, the solder paste will be solidification very easily if don’t put the ceramic PCB on heating table

For some small LED, it can’t be put by SMT machine, because no such small feeder to pick it up, then need to put it on board by hand.

We can do very well for the small BGA components too.

Below some photos of ceramic PCB.

If you would like to know more about ceramic and ceramic PCB SMT, please feel free to email me

Ceramic PCB with SMT 1
Ceramic PCB with SMT 2
Ceramic PCB with SMT 3
Ceramic PCB with SMT 4
Ceramic PCB with SMT 5

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Aluminum vs Copper Core PCB

Wednesday, May 19th, 2021

In Best Technology, currently the most common metal used for Metal Core PCB manufacturer are Aluminum, Copper. Today let’s talk about the main differences between aluminum substrate and copper substrate, hoping to help you choose the right substrate in future design projects.

Although they both share similar properties and functions, there are still a few variations between the two kinds of metals. Some of the key differences between aluminium and copper core PCBs are explained in the points below.

1. Thermal Conductivity

The thermal conductivity of copper substrate is up to about 400(W/mK) and the thermal conductivity of aluminum substrate is generally about 200W(W/mK). The thermal conductivity is higher, the transfer efficiency will be better, and the heat dissipation will be better, then the working life will be longer.

 Thermal Conductivity

2. Electrical Conductivity

Both aluminum and copper, being metals, are electrical conductors of electricity, although the exact degree of this varies between the two metals. When it comes to electrical conductivity, copper has a clear advantage over aluminum. In other words, in applications where there is a need for efficient electrical conductivity, copper makes for an ideal pick.

 Electrical Conductivity

3. Electrical Resistance

Resistance is very important when it comes to PCB design, as it can have an effect on the overall function and stability of the component. Given that copper has a higher density than aluminum, it tends to have a lower resistance than aluminum, so copper is an better choice where there’s a requirement for thinner circuits and faster electricity transfer.

Electrical Resistance

4. Weight

Since copper has the higher density for per unit area, the weight of copper PCB is much heavier than aluminum PCB for the same design.

In applications where light-weight construction is required more than anything else, aluminum is the preferred material of choice. On the other hand, applications where weight is not much of an issue, tends to be the ones where copper is widely used.

Weight

5. Application

Copper core PCB is the best heat dissipation among all MCPCB, so it’s mostly used in automobile headlights, taillights and some high-tech electronic products (unmanned aircraft, mining machine) high-power lighting equipment. The aluminum core PCB is mostly used in indoor lighting, energy saving lighting, street lighting and other energy-saving lighting electronic products.

Application
Application

In conclusion, due to the above different parameters and performance, the cost of copper is generally more expensive than aluminum. If you have other questions about MCPCB, welcome to contact us .

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How to Test for an Open Short Circuit on a PCB?

Tuesday, May 18th, 2021

Every printed circuit board need to do full test before ship to our customer. but you may have doubt, the PCB was made according to the original Gerber file, why finish the PCB production process, why the short Circuit will occur on a FR4 circuit board?

A short circuit may also occur during reflow soldering. the solder paste may accidentally connect two pins that are very close to each other. In some cases, errors can occur during the PCB design process because the wiring between different networks accidentally connects.

We believe every PCB manufacture have their own test method to do short circuit, but today I would like share how Best Technology to Check for Short Circuits in a Printed circuit board.

Here are some important steps:

Step 1 Visual inspection

The first step for locating short circuits on PCB is to carefully look at the entire surface of the PCB. Best Technology QC guys use a magnifying glass or low magnification microscope during the circuit board examination. We check the whole board surface to see if there are some traces break off. Any cracks or blobs of solder should get careful attention. Check all your vias. If you specified unplated vias, make sure that’s the case on the board. Poorly plated vias can create a short circuit between layers and leave you with everything tied to ground, VCC, or both.

visual inspection

All the testing work will carry out according to IPC 6012 class 2.

Step 2 Use a Digital Multimeter to find out where is the problem

To test a circuit board for a short circuit, you need to check the resistance between different points in the circuit. If visual inspection doesn’t reveal any clues as to the location or cause of the short circuit, grab a multimeter and try to track down the physical location on the printed circuit board. The multimeter approach gets mixed reviews in most electronics forums, but tracing your test points can help you figure out what isn’t the problem.

Step 3 use Probe flying Tester &E-tester

As long as you are in Printed Circuit board field, you are definitely known Probe flying test and E-Teter.

Flying probe test systems require no test fixture, it can serve both prototype and small production, providing maximum flexibility for PCB manufacturers and this job can complete in a short time.

probe flying test
probe flying test-1

But when your circuit board become to volume, you will need to open a test tooling/test fixture to test the Printed Circuit board to test the open short circuit.

E-tester

In my next blog in June, I will introduce Probe flying test to you in more detail.

If you have any question about printed circuit board, you are welcome to contact Best Technology.

It is our great pleasure to communicate with you for any issue for printed circuit boards.

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What is Blind Via and Buried Via for Printed Circuit Board?

Thursday, April 15th, 2021

In the Printed Circuit Board industry, believe that you are familiar with blind via and buried via. What is blind via and buried via for PCB? And do you know is the Blind via or Buried Via have special application in your Printed Circuit Board?

In order to know more, we would like to share more information with you today.

Best Technology is an experienced FR4 PCB manufacturer in China since year 2006, with more than 15 years design and fabricate experience for PCB, Best Technology accumulated more than 1000 customers from all over the world.

Before start, we need to know what kinds of hole for FR4 Circuit Board, Via, Blind Via and Buried Via.

What is a Via?

Vias are the copper-plated holes in the PCB that allows the layers to layer connection. The standard via is called a through-hole via, but there are several disadvantages to using through-hole vias in Surface Mount Technology (SMT). For this reason, we often use a blind via or buried via instead. A blind or buried via can be processed in a wide range of different measures, including plugged copper mask via, a plugged solder mask via, plated via or staggered via.

Via
staggered via

What is Blind Via?

The via connects the external layer to one or more inner layers of the PCB and is responsible for the interconnection between that top layer and the inner layers.

Blind Via

What is Buried Via?

For a buried via, is the inner HOLE, between both sides in the board up and down inside the layer after pressing is cannot see. So, it doesn’t have to take up the outer area.

Buried Via

Blind and buried vias are particularly advantageous in HDI board because they optimize the density of the boards without increasing board size or the number of board layers you require. They are most commonly used in high-density PCB designs like, or in FPGA and custom chip packaging.Here is the photo which Best Technology took from our production line to make HDI Printed Circuit Board for our USA customer.

HDI board under production
HDI process

Best Technology is a very professional manufacturer in printed circuit board and HDI Board. If you are interesting to know more information of us, come to contact us and we are looking forward to discuss with you more for Printed Circuit Board.

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