How to make Panel for MCPCB?

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.

Laser drilling and cutting in the production process of ceramic circuit boards

July 12th, 2021

In the ceramic circuit board processing and production process, laser processing mainly includes laser drilling and laser cutting.

Ceramic materials such as alumina and aluminum nitride have the advantages of high thermal conductivity, high insulation and high temperature resistance, and have a wide range of applications in the fields of electronics and semiconductors. However, ceramic materials have high hardness and brittleness, and its molding and processing are very difficult, especially the processing of micropores. Due to the high power density and good directivity of the laser, lasers are generally used to perforate ceramic plates. Laser ceramic perforation generally uses pulsed lasers or quasi-continuous lasers (fiber lasers). The laser beam is focused on On the workpiece placed perpendicular to the laser axis, a laser beam with high energy density (105-109w/cm2) is emitted to melt and vaporize the material. An air stream coaxial with the beam is ejected by the laser cutting head to remove the melted material from The bottom of the incision is blown out to gradually form a through hole.

Due to the small size and high density of electronic devices and semiconductor components, the precision and speed of laser drilling are required to be high. According to the different requirements of component applications, electronic devices and semiconductor components have small size and high density. Due to its characteristics, the precision and speed of laser drilling are required to be high. According to the different requirements of component applications, the diameter of the micro-hole is in the range of 0.05 to 0.2 mm. For lasers used for ceramic precision processing, generally the focal spot diameter of the laser is less than or equal to 0.05mm. Depending on the thickness and size of the ceramic plate, it is generally possible to control the defocus to achieve through-hole punching of different apertures. For through-holes with a diameter less than 0.15mm, drilling can be achieved by controlling the defocus amount.

There are mainly two types method for cutting ceramic PCB: waterjet cutting and laser cutting. Currently, fiber lasers are mostly used for laser cutting. Fiber laser cutting ceramic circuit boards has the following advantages:

(1) High precision, fast speed, narrow cutting seam, small heat-affected zone, smooth cutting surface without burrs.

(2) The laser cutting head will not touch the surface of the material and will not scratch the workpiece.

(3) The slit is narrow, the heat-affected zone is small, the local deformation of the workpiece is extremely small, and there is no mechanical deformation.

(4) The processing flexibility is good, it can process any graphics, and it can also cut pipes and other special-shaped materials.

Al2O3 PCB with drilling
AlN PCB with drilling

 Under the development trend of light and thin, miniaturization, etc., the traditional cutting processing method has not been able to meet the demand due to the insufficient precision. Laser is a non-contact processing tool, which has obvious advantages over traditional processing methods in cutting process, and plays a very important role in the processing of ceramic substrate PCB.

Please contact sales@bestpcbs.com if you want to know more ceramic PCB.

What is E-Tester for Printed Circuit Board?

July 11th, 2021

When the bare Printed Circuit Board qty become volume fabrication, the PCB manufacture will not use the Probe flying tester to test the PCB circuit board. Best Tech will make new PCB test fixture to test the bare PCB, The electrical Test (E-test), which is the final electrical test to verify net continuity and the absence of shorts on the bare printed circuit boards (PCBs). In Best Tech PCB factory, we perform 100% electrical testing on all bare PCBs its facilities as per IPC-6012 class 2 standard. And from the following photo in computer, you can see it will show PASS for PCB.

in test

in test

To test the PCB boards, we require the NETLIST file. Normally we create a reference netlist file from the customer’s original Gerber files during PCB fabrication.

We always prefer to receive the CAD file based on the netlist for comparison. Since a CAD based netlist is generated before PCB routing, it provides another layer of checking (against the Gerber files). This allows us to catch any PCB faults introducing in the event of an error in the Gerber files. For full turnkey PCB assembly (PCBA service) projects, this helps to ensure that the PCB boards are 100% correct before any components are populated.

tester 2

tester2

Here are Best Tech E-tester Capabilities

Minimum Continuity Resistance0.1 Ohms
Maximum Test Voltage1000 Volts
Max Isolated Resistance25 M Ohm – 2 G Ohm
Electrical Test Pitch (Fixture)20mil(0.5mm)
Electrical Test Pitch (Flying Probe)4mil
Debug /check for missing pins: (Test fixture)10 minutes
Test time per board:40 seconds
Setup time:30 minutes

All points are tested simultaneously. However, this process involves set-up to create the fixture itself and additional costs associated with the cost of materials.

The electrical test fixture has a limited shelf life and repeat using times. For every PCB it will need a fixture and its custom-made for a customer only. Many other factories only store 2 years shelf life for electrical test fixtures, but Best Tech will store at least 3 years for customer.

In order to ensure the quality of fixtures and spare enough space to store fixtures, Best Tech leaves one floor to keep the fixture. See attached fixture photo.

tester 1

tester1

During the 3 years’ time, customer no need to pay the fixture charge again if the update is no update. The flexible test fixture shelf-life policy, it will help customer save the cost.

At the end of the PCB production process, we use electrical test to check the interconnectivity of the PCB is correct against the original board data.

Best Tech did the E-Tester to test the PCB 100% before delivery to customer, this makes Best Tech get highly comments from our customer on the world with good printed circuit board quality and best service. See the customer highly comments of Best Tech.

customer highly comments on our service

customer highly comments on our service

You are warm welcomed to contact Best Tech to discuss about the Printed Circuit Board (PCB).

What is IPC standard for PCB?

June 28th, 2021

Do you know what is IPC standard for PCB?

IPC, it is a trade association whose goal is to standardize the assembly and production requirements of electronic devices and components.  It was established in 1957 as the Institute of Printed Circuits.  IPC has developed thousands of standards and specifications to regulate the electronics manufacturing industry

IPC standards are related to PCB design, production technology, electronic assembly, etc., in order to achieve high reliability, high quality, high performance, and meet user specifications.

For PCB manufacturing, do you know which IPC standards are commonly used?

multilayer pcb

Here I would like to share you some standards which we mainly use:

  1. 1. IPC-6011: General Performance Specification for Printed Boards
  2. 2. IPC-6012: Appraisal performance and specifications for Rigid printed boards
  3. 3. IPC-6013: Appraisal performance and specifications for Flexible printed boards
  4. 4. IPC-6016: Fixed performance and specification of HDI or printed circuit board of high density interconnection layer
  5. 5. IPC-SM-840: Appraisal and performance of permanent performance
  6. 6. IPC-HM-860: Multilayer Hybrid Circuit Specification
  7. 7. J-STD-003: Solderable test for printed boards
  8. 8. IPC-A-600F: Acceptance conditions for printed boards
  9. 9. IPC-A-61: Acceptability of electronic components
  10. IPC-4761: Design Guide for Protection of Printed Board Via Structures

One of the most widely used industry standards in the manufacturing of printed circuit boards is IPC-A-610—Acceptability of Electronic Assemblies. … IPC-A-600—Acceptability of Printed Boards. This standard is used primarily for the incoming inspection of bare boards from a PCB fabricator.

In the IPC-A-610C document, electronic products are divided into level 1, level 2, and level 3. The higher the level, the stricter the quality inspection conditions. Here are how 3 levels divided:

Level 1 products: called general-purpose electronic products. Including consumer electronic products, certain computers and their peripherals, and products whose main purpose is to use functions.

Level 2 products: called dedicated service electronic products. Including communication equipment, complex industrial and commercial equipment and high-performance, long-life measuring instruments. Under normal use environment, this kind of product should not malfunction.

Level 3 products: called high-performance electronic products. Including high-reliability, long-life military and civilian equipment that can continue to operate. This kind of product must not allow any interruption failure during use, and at the same time, it is necessary to ensure the reliable startup and operation of the equipment in a harsh environment. Such as medical life-saving equipment and all military equipment systems.

resin filled production bpm20599

It is no problem for us to manufacture the PCB following the standard in IPC 6012 /6013 Class 2 and Class 3, as well as following to the standard listed above/

These acceptance conditions are the basis for the inspection of our company’s products, as well as the working standards of the employees at the production site, and also become an important part of the training of the employees for PCB production and assembly in our company.

Send us your PCB drawing, let’s help to make your PCB design into a real board.

The technology and application of DBC ceramic PCB

June 17th, 2021

DBC means direct bonding copper, it is a ceramic surface metallization technology.

The copper is bonded on Alumina, Beryllium Oxide and Aluminum Nitride, Packaging applications for power electronic modules, semiconductor refrigeration and LED devices are widely used.

DBC-Ceramic-PCB

96% Al2O3 has good insulation, good chemical stability, high strength, and low price. It is the preferred material for DBC technology, but the thermal conductivity of aluminum oxide is low, and there is a certain thermal mismatch with the thermal expansion coefficient of Si.

BeO is a good ceramic material used in DBC technology. It has high low-temperature thermal conductivity. It can be used for medium and high power devices. In the application field and process, the toxicity caused by it should be properly protected.

AlN material is non-toxic, moderate dielectric constant, thermal conductivity is much higher than aluminum oxide, close to beryllium oxide, and thermal expansion coefficient close to SI. All kinds of chips and high-power devices can be directly attached to the AlN substrate. No transition layer of other materials is used. The prospects currently used in DBC technology are very promising.

There is no any layer between the metal and ceramic substrate, so the thermal diffusion ability is strong; the contact resistance is also low, which is conducive to the connection of high-power and high-frequency devices.     

The linking temperature is lower than the melting point of copper, and the DBC substrate maintains a stable geometric shape during the connection process. In some cases, the copper foil can be made into the required shape before the linking, and then the DBC preparation process is performed, eliminating the need After connecting the etching process.

The copper conductor part has a very high current-carrying capacity, so it has the ability to reduce the size of the intercepting medium and increase the power capacity.

If you want to know more about DBC ceramic PCB, please feel free to contact sales8@bestpcbs.com

Common Problems in SinkPAD Board Design

June 17th, 2021

1. What is the SinkPAD Board?

Sink Pad Board, also called Heat Sink or DTP (direct thermal path), it’s an alternative PCB technology to the conventional metal core PCB providing direct thermal path solutions for high power LED. 

The thermal conductive PAD is convexity area of copper core/pedestal, so that the thermal PAD of LED can touch the convexity area of metal core directly, and then the heat of LED will be dissipated into the air much faster and more efficient than conventional MCPCB.

Heat Sink

2. If only the LED pad can be made as SinkPAD?

Of course no, the pads of other chips or components also can be designed as Sink PAD, one of the most common is the IC pad. In some designs, IC needs to pass through the large current and it will emit a lot of heat, it would be best to design its pad as a thermal conductive pad at this time.

SinkPad Board after SMT

3. What is the thermal conductivity of a SinkPAD ?

The thermal conductivity could be 235 W/m.k to 400 W/m.k.

4. Can we use SinkPAD technology for any LED packages?

No, it’s designed to be used with the LEDs which has electrically neutral thermal pad. Such as Cree XPL/XML/XHP/XPG/XPE/XPC/XTE/XBD, Luxeon Rebel & Luxeon M from Philips Lumiled, Oslon SSL & Oslon square from Osram, Nichia N219, Seoul Semiconductor Z5P / Z5M, Samsung 3535, Bridgelux SM4, etc.

5. What is the Manufacturing Process for the SinkPAD Board?

Manufacturing process is the same as conventional MCPCB, please click here to see the manufacturing process status.

Shinkpad

6. How does SinkPAD Board compare to Conventional MCPCB?

Conventional MCPCB uses a thermally conductive dielectric layer to bond circuit layer with base metal (Aluminum or Copper) layer. The key to thermal performance of MCPCB lies in its dielectric layer. Even though thermally conductive dielectric has higher thermal performance compared to normal FR4, it’s still a weakest link in the conduction thermal path.

SinkPAD Board approach overcomes this limitation, which provides “Direct thermal path”, the LED Chip can directly contact the copper substrate, there’s no dielectric between LED thermal pads and the metal base, then the thermal resistance is very small.

7. Can the aluminum be made as the base of Heat Sink?

Actually yes, however, regarding of current technical conditions, since aluminum or aluminum alloy cannot directly react with acid, the reaction process is too complex and difficult to control, which will increase the difficulty of etching the LED pad platform.

Considering the scrap rate, the process of etching LED pad platform with aluminum is more complex and the overall cost is higher, and the copper also dissipates heat much better than aluminum, so copper is generally used as the substrate for Heat Sink in our company.

Copper Substrate

8. Does SinkPAD Board require special PCB design?

No, we can use your existing MCPCB Gerber data.

Welcome to contact us if you have other questions about Sink Pad Board. 

What is flying probe test printed circuit boards?

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.

How to do SMT for ceramic PCB

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

Aluminum vs Copper Core PCB

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 .

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

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.