Archive for the ‘FAQ’ Category

How to avoid circuits issue while the production process ?

Monday, July 13th, 2020

As we all know, the short & open circuits is a very common issues for the Printed Circuits Board, especially for the extra thin PCB, because its substrates thickness are very thin, generally from 0.4mm-0.15mm, so the circuits will be easy to be broken if we didn’t control the production process well.

So, you may want to know, as an experienced PCB manufacturer, what we will do to avoid the circuits issues?

Here let me show you what we do:

Firstly, after the process of copper plating, we will put the boards into our washing line to remove those drilling burr, surface oxide layer, etc.  To make sure the boards are fully clean before start the traces making process.

pcb washing
pcb washing

Actually, most of the open and short circuits problem are caused by the film scratching, so each operation while the pattern transfer process is very important.

That’s also why the exposure and developing need to be processed in the dust-free workshop. We will use the rack to place each PCB board separately, to avoid the touching between PCB.

pcb explosure and developing
pcb explosure and developing

After the circuits etching out, we will take the boards to do the AOI testing, to check if there are any broken circuits, short gaps, protrusions, copper surface garbage and other problems. If there is, our machine will alert the problem, and we will fix the problem or scrap the defectives boards, with this process to prevent the defective boards move to the next step.

Most importantly is that we will do the first article inspection for all the boards, as long as we found the circuits issues while the AOI process, we will not take the whole batch boards go ahead.

aoi testing
aoi testing

Besides, the operation standard while the etching process is also very important for how the traces being. So, our production team will control the running speed of the etching machine very strictly. If it is a PCB with o.5oz bottom copper , only allow walk 1.4 meters at per minute, if 2oz, walk 0.8m one minute.

etching pcb
etching pcb

Except above process, all the boards will be required to do a final electrical testing before move to the packing. For prototypes, we will use flying probe testing. For volume, we will open the E-testing fixture to do the testing.

In our company, for the extra thin PCB, if the boards thickness lower than 0.2mm to do the flying probe testing, it needs to be tested before the outline process, because the boards are too thin to support the boards well while the flying probe, it will fall down easily.

flying probe testing and electric testing
flying probe testing and electric testing

Of course, our QC people will do the double visual inspection to make sure all the boards are being well made.

fr4 pcb inspection
fr4 pcb inspection

We always try our best effort to prevent any defective boards send to customers.  

Quality and Customers Scarification, it is always our company’s pursuit.

How to improve the gap between the convexity and LED pad?

Saturday, July 11th, 2020

About the SinkPad copper core PCB, all is known that convexity is very important, the height of convexity is about 0.2mm-0.25mm.

We need to know what’s the reasons caused the gap between the convexity and LED pad is big.

  1. We make the copper core with convexity firstly, then make the circuit/panel board (FR4PCB/BT PCB) and finally do the lamination for cooper core and circuit board.
  2. The tolerance for convexity is +/-0.05mm-0.075mm.
  3. The tolerance for circuit/panel board is +/-0.13mm.

If we do negative tolerance for convexity and positive tolerance for circuit/panel board, then it will cause the gap very big.

See below picture and details.

For example, the size of convexity is 0.5mm, after negative tolerance -0.075mm, it will be 0.425mm and each side will be 0.0375mm smaller.

For the circuit/panel board, the gap between convexity is 0.2mm, after positive tolerance +0.13mm, it will be 0.33mm and each side will be 0.065mm bigger.

So finally, the gap will be 0.2mm+0.0375+0.065mm=0.3025mm. It is about 50% bigger than original size.

sinkpad pcb
sinkpad pcb
sinkpad pcb
Big gap between convexity and LED pad

How to improve that problem?

  1. Making the copper core with convexity according to design.
  2. Measuring the dimension of convexity before making the circuit/panel board, then making the circuit/panel board according to the convexity dimension with compensation design.
  3. Do Positive tolerance for convexity and negative tolerance for circuit/panel board, the gap will be much more smaller.

For example, the size of convexity is 0.5mm, after negative tolerance +0.075mm, it will be 0.575mm and each side will be 0.0375mm bigger

For the circuit/panel board, the gap between convexity is 0.2mm, after positive tolerance -0.13mm, it will be 0.07mm and each side will be 0.065mm smaller.

So finally, the gap will be 0.2mm-0.0375-0.065mm=0.0975mm. It is about 50% smaller than original size.

dtp pcb
dtp pcb
DTP PCB
Good gap between convexity and LED pad

For more information about SinkPad PCB, please click

https://www.bestpcbs.com/products/multi-layer-sinkpad-board.htm

In order to reduce the cost, can SinkPad PCB use aluminum base instead copper base for heat dissipation?

Wednesday, June 24th, 2020

SinkPad PCB is a type of Copper base PCB used in thermoelectric separation application. It generally used for high power LED, the pad of LED touch the copper base directly, so that the heat generated by LED will dissipate quickly, which can achieve the best heat dissipation and conduction.

sinkpad gerber
sinkpad gerber
sinkpad pcb
sinkpad pcb

In another words, it is a technology that require to increase the path of the LED pad to the copper base to accelerate the heat emission from the base material. The copper base is vital while it also cost higher.

Then in order to lower cost, can SinkPad PCB use aluminum base instead copper base for heat dissipation?

The answer is NO. As you can see the below manufacturing steps, the SinkPad will etch the copper base into convex platform with Copper Etching Solution, then hollow out the Double Layer FR4 PCB, and do lamination with the convex platform.

sinkpad pcb manufacturing steps
sinkpad pcb manufacturing steps

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.

Why don’t use BeO as substrate to make DBC ceramic PCB?

Monday, June 22nd, 2020

It is widely known that BeO with high thermal conductivity (200-250W/m.k). High dielectric constant 6-7 (0.1MHz) and dielectric loss tangent is 10-4 (0.1GHz), extremely high working temprature. It is ideal material for ceramic PCB, lots of engineers want to use it as DBC ceramic PCB substrate.

But it is not popular in ceramic PCB market, comparing with Al2O3, AIN, Si3N4, or ZrO2, as the powder of BeO is extremely poisonous.

The poison gas is produced by the reaction between oxygen, Cu and BeO under 1065-1085 degrees Celsius, so it is limited to make cooper on BeO substrate, it has caused ALN (Aluminium Nitride) is becoming more and more popular.

Right now, only few countries are using BeO to make ceramic PCB, such as USA, Russia and China. USA had biggest capability to make BeO , and here in China, there’re still some companies to make BeO raw material and among them, a few companies to produce direct copper bonded (DCB) on BeO because of environment limitation.

Though BeO is not popular for DBC technology, but it is feasible for thick film technology, because when the mentalization of Ceramic PCB, the conductor (Au or AgPd) on BeO substrate was made by silk-screen printing, and drying temperature is only around 850C, no need to under high temperature environment, so there is no chemical reactions, no environment issue.

Below the thick film ceramic PCB manufacturing process for your reference.

https://www.bestpcbs.com/products/thick-film-ceramic-pcb-manufacturing-process.htm

Here is the photo of BeO with AgPd conductor.

BeO with AgPd conductor
BeO with AgPd conductor

Welcome to contact us if you have better idea, or different comments on BeO ceramic PCB, communation will make us becoming better and better.

How to clean the PCB assembled boards after soldering?

Friday, June 19th, 2020

Best Technology is a full turn-key assembly service company, we can supply the assembled board with very nice and clean surface.

Do you want to know how we control the cleaning process of PCBA? We would like to share the full cleaning process.

As we know, flux is used when soldering electrical components to a printed circuit board.

After assembly process finished, we need to remove all the unnecessary flux paste or other solder flux/ residue in order to avoid any quality issue.

Although it is a simple work, but to prepare some tools and preparation is necessary and important. Like wash board water, dust-free cloth, brush,Tweezers, static bracelets, finger gloves

Here is the how the cleaning process we made:

Step1:  

Use brush to brush the solder joint and solder flux on the soldered PCB. Applying some alcohol or acetone onto the brush, do not use too much pressure, as this may cause the solder point to break. Repeat the procedure as necessary, to remove remaining flux residue on the PCBA.

PCB assembly
Step1: Brush the solder joint and solder flux on the soldered PCB

Step2:

Wipe with a clean dust-free cloth to clean the assembled PCB.

Keep board clean and tidy to make sure no impurities and finger marks. Do the same process for bottom side.

PCB assembly
Step2:Wipe with a clean dust-free cloth to clean the assembled PCB.

Step3:

When above step finished, keep the board for an extra day to let the board dry enough before packing. Best QC guys will do final inspection for the finger prints under light. this will be helpful to check the cleaning result further.

PCB assembly
Step3:  final inspection for the finger prints under light

Step4:

Finally, use dust-free cloth to do the final cleaning and let the board dry and clean enough before package.

PCBA Cleaning process
Step4: use dust-free cloth to do the final cleaning.

Above are the process for how we clean the assembled boards.

Best Tech is a very professional manufacturer in printed circuit board and assembly. We clean each of assembled boards as the procedure we showed above.

If you are interesting to know more process for how we control the quality for the PCB assembled boards, contact us at any time, we will show you more.

What kind of finishing recommended for the extra thin FR4 PCB

Thursday, June 18th, 2020

As we know, the extra thin PCB means the thickness of printed circuit board is more thin than normal PCB, which is refer to a thickness smaller than 0.4mm for 1L/ 2L & 4L PCB. For extra thin PCB, we know they are all very thin and are easily to be broken, so the option for the surface treatment of the extra thin PCB is very crucial.

So, what kind of finishing to be recommended for the extra thin Rigid PCB?

extra thin FR4 PCB
0.15mm extra thin FR4 PCB_Best Technology

Generally, there are 3 kinds finishing can be recommended for the extra thin PCB. It is OSP, ENIG (Electroless Nickel Immersion Gold), and ENEPIG.

extra thin pcb finishing
extra thin pcb finishing

But you may want to ask that lead-free Tin is also a common finishing for the PCB. Why not recommend LF HASL? 

That’s because while LF HASL Process, the PCB will be easy to be blew away, people will use heated compressed air to leveling (blowing) on the coating molten tin (lead) solder, during this process, the traces will be easy to be broken as well.

So normally, we will not recommend the LF HASL finishing for an ultra thin FR4 PCB.

HASL lead-free is only suitable for a board with minimum thickness of 0.6mm, while the standard gold immersion surface coating can support PCB with a minimum thickness of 0.2mm. For the surface treatment of ENEPIG , which plate only needs to be about 0.1 microns for palladium and about 0.1 microns for gold, (palladium is a precious metal that is much harder than gold), so for board with ENEPIG finishing, its surface will looks more smooth, that’s also why it is the most recommended surface treatment for an extra thin PCB.

extra thin PCB
0.13mm extra thin Rigid FR4 PCB_Best Technology

If you are searching for an extra thin PCB, feel freely to ask or send your inquiry to us. We will be pleased to share you more information regarding the extra thin PCB.

What is SinkPad PCB?

Wednesday, June 17th, 2020

SinkPad PCB, also called Heat Sink or DTP (direct thermal path) PCB, it is a type of Copper base PCB used in thermoelectric separation application. It generally used for high power LED, the pad of LED touch the copper base directly, so that the heat generated by LED will dissipate quickly, which can achieve the best heat dissipation and conduction.

SinkPad PCB
SinkPad PCB

Thermoelectric separation technology is based on the higher heat dissipation requirements of high power electronic products, which needs to meet two basic conditions:

1.LED pad touches the base substrate directly.

It means we need to increase the path of the LED pad to the base substrate to accelerate the heat emission from the base material.

Two layers SinkPad PCB Stack up
Two layers SinkPad PCB Stack up

2.Higher heat dissipation substrate materials

Copper has a thermal conductivity of 401W/m·K, while aluminum has a thermal conductivity of 237W/m·K. Obviously, copper has better thermal conductivity because of its high density, high mass. Therefore, a SinkPad PCB usually means a SinkPad copper base PCB.

Why do High Power LED mostly use COB light sources? What are the advantages?

Tuesday, June 16th, 2020

If we observe carefully, we will find that most of the high-quality surface light lamps in the market use COB light source, such as LED spotlights, Automotive, LED Backlight for LED TV, etc. What are the advantages of such choice?

Automotive
Automotive
LED Backlight for LED TV
LED Backlight for LED TV
LED spotlights
LED spotlights

First of all, we need to how the COB differ from the common MCPCB. “Chip-On-Board” Metal Core PCB is a type of MCPCB used in thermoelectric separation application. By using COB, the micro-chip (also known as “die”) directly touch the metal core where the heat dissipate, and electrically interconnect the trace of circuit board (wire-bonding) so that power supply can be provided.

Stack up
Stack up

Advantages of utilizing COB MCPCB over common MCPCB:

  1. High thermal conductivity(137W/m.K), High insulation, High pressure resistance
  2. High reflectivity: mirror aluminum≄98% (The reflectivity of Taiyo Soldermask used in common MCPCB is 75-80%, the highest is only 90%)
aluminum pcb
BAS15191
metal core pcb
BAS15192

Since the COB is packaged directly on the MCPCB, it’s easy assembly for high powers LED, direct heat dissipation through the substrate can not only reduce the manufacturing process and cost of the bracket, but also have the advantage of reducing heat dissipation resistance. So the spotlight produced by COB technology will be lighter, more flexible and able to realize more possibilities on the stage.

If you are also interested in COB, please feel free to contact me, I’m looking forward to communicating more with you.

You’re welcome to visit our website to learn more about us. https://www.bestpcbs.com/products/COB-MCPCB.htm

What is high Tg PCB (fr4-170TG, TG 130-140, FR4 Tg150)

Thursday, June 11th, 2020

In recent years, there are more and more customers request to manufacture PCB with high Tg, in the following we would like to describe what is high Tg PCB.

fr4 170tg
fr4 170tg

Normally high Tg refers to high heat resistance in PCB raw material, the standard Tg for copper clad laminate is between 130 – 140℃, High Tg is generally greater than 170℃, and middle Tg is generally greater than 150℃. Basically the printed circuit board with Tg≄170℃, we call high Tg PCB. As the rapid development of electric industry, especially for the computer as the representative of electronic products, developing toward the high performance, high multilayer requires PCB substrate material with higher heat resistance to ensure high reliability. On the other hand, as a result of development of SMT, CMT with high density pcb assembly technology, the PCB manufacturing with small hole size, fine lines and thin thickness are more and more inseparable from the support of high heat resistance.

fr4 170tg
fr4 170tg

If the Tg of PCB substrate is increased, the heat resistance, moisture resistance, chemical resistance and stability of printed circuit boards will be improved as well. The high Tg applicates more in the lead free pcb manufacturing process.

Therefore, the difference between general FR4 and high Tg FR4 is, in the hot state, especially in the heat absorption with moisture, the high Tg PCB substrate will perform better than general FR4 in the aspects of mechanical strength, dimensional stability, adhesiveness, water absorption and thermal decomposition.

We will be exhibiting at electronica Munich 2020

Monday, June 8th, 2020

Best Technology, a China- based assembly manufacturer will be exhibiting at electronica Munich 2020 in Bavaria, Germany at booth No. 623(Hall B1) from November 10, 2020 to November 13, 2020(Western Time). Actually, we have participated in this exhibition for continuous 2 years. Here are some pictures for your reference.

pcb exhibition
pcb exhibition
pcb exhibition
pcb exhibition
pcb exhibition
pcb exhibition
pcb exhibition
pcb exhibition

At our exhibition booth, attendees will be able to learn more about our company for PCB manufacturing and PCB assembly technology.

For interested professionals, Best Technology had on hand experts to offer detailed insights and experience on PCB assembly, covering PCB prototype and low/high-volume production. For more information on PCB assembly and fabrication, welcome to visit our booth.

You will see 10mm to 1,500 mm flexible circuit board, from 2 layer rigid-flex circuit to 50 layers, 1/2 OZ copper to 3 OZ, 0.15mm extra thin FR4 PCB to 30 OZ heavy copper, turn-key service from components sourcing,board fabrication(FPC, PCB, MCPCB, Ceramic PCB) and final assembly with programming and testing and metal dome that is used in conjunction with a printed circuit board, flex circuit, or membrane, become normally-open tactile switches. we have four types of metal domes: four legs with size from 5mm-20mm; triangle with size 4mm-12mm; round dome with size 4-16mm, oblong dome with size 3.7mm-58.1mm, and we also make dome with adhesive, named dome array.

You are warmly welcome to see how we can manage the components wastage and efficiency to help save your time, money and energy.

About electronica Munich:

Electronica is the international trade show for electronic components, systems and applications and shows the full range in all its diversity in width and depth as the world’s leading trade fair. It reflects the high degree of innovation throughout the industry. Exhibitors and users in the areas of systems, applications and technologies of electronics can receive the information of the latest innovations and developments in the fields of system peripherals, power engineering to printed circuit boards or EMS.

Welcome to visit us at Booth 623 from November 10, 2020 to November 13, 2020(Western Time).

electronica 2020
electronica 2020