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Do the vias can be filled for ceramic PCB?

November 13th, 2020

As everyone knows for FR4 PCB, people like the vias to be tented or filled for some special applications.
Ceramic PCB is more and more popular because of the thermal conductivity is very high and very good for heat dissipation. Most of customers are going to make the PCB with ceramic material, includes Al2O3, AlN, BeO or Si3N4, etc.
So do the vias can be filled for ceramic PCB becomes the frequently asked questions (FAQ).
The answer is YES.
So what’s the material can be filled in vias for DBC/DPC alumina PCB/ Aluminium Nitride PCB?

The material can be solder mask, Dow Corning 1-4173 and copper/Cu.
Normally, customers want the vias/holes to be filled with copper.
Because copper can fill the vias very well and it is easier to do and it looks very good. Please see below photo.
The left one with filling with copper, the right one without filling copper

Why you need to fill the vias with copper?
1.Becuase if let the vias open, they will allow solder to flow through to opposite side of PCB during reflow, this causes bridging under components.
Filling the open vias/holes with copper can prevent from the solder pates into the vias.
2.If you need to pull vacuum around them and a hole would compromise that, so need to fill the vias.
There are also other purposes for filling the vias, if you need such ceramic board with filling the vias, please contact Coco in Best Technology sales@bestpcbs.com

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Posted in Ceramic PCB, DBC substrate, PCB News, PCB Technology | No Comments »

What are the commonly used aluminum base materials? What’s the difference?

November 11th, 2020

Best Technology has more than 14 year experience for producing Metal core PCB, we have our own raw materials factory for MCPCB and we fabricate MCPCB in Shenzhen, so that customer various special requirements can be meet here.

Compared to copper and stainless steel, aluminum is the most economic option considering thermal conductivity, rigidness, and cost. And many of these aluminum alloys base have been divided into classes, the commonly used on MCPCB are AL1060, AL3003, AL5052 and AL6061.

Do you know the differences between these substrates? This blog will give a brief introduction for you.

1060 alloys
AL1060 are commercially pure, unalloyed aluminum, it’s soft, ductile, workability and exceptional corrosion resistance, making it suitable for hard-forming applications. It can be welded with any method, but it cannot be heat-treated. Its cost is the lowest of the four types.

3003 alloys
AL3003 use silicon, copper, and magnesium as the main alloying elements, oftentimes with supplemental nickel and beryllium. They are heat treatable, have high strength, good resistance to cracking and wear, and have good machinability.

Mechanical PropertiesMetricEnglish
Ultimate Tensile Strength200 MPa29000 psi
Tensile Yield Strength186MPac
Shear Strength 110 MPa16000 psi
Modulus of Elasticity68.9GPa10000 ksi
Shear Modulus25 GPa3630 ksi

5052 alloys
AL5052 use magnesium as their primary alloying element and are not heat-treatable, but it’s the highest strength alloy of the more non-heat-treatable grades. Its resistance to fatigue is better than most grades of aluminum and have a great surface aesthetic when anodized.
In our company, if not special request or notes, the default material we use is AL5052 after considering all the performance and cost.

Mechanical PropertiesMetricEnglish
Ultimate Tensile Strength228 MPa33000 psipsi
Tensile Yield Strength193 MPa28000psi
Shear Strength138 MPa20000 psi
Modulus of Elasticity70.3GPa10200 ksi
GPaShear Modulus 25.9 GPa25.9 760 ksi


6061 alloys

Mechanical PropertiesMetricEnglish
Ultimate Tensile Strength310 MPa45000 psi
Tensile Yield Strength276 MPa40000 psi
Fatigue Strength207MPa30000 psi
Shear Strength96.5MPa14000 ksi
Modulus of Elasticity68.9 GPa10000 ksi
Shear Modulus26 GPa770 ksi

AL6061 implement magnesium with silicon as their principal alloying elements. Their strength is improved with heat treatment. AL6061 is one of the most widely used aluminum alloys, it has high strength and superior corrosion resistance. Its weld-ability and formability make it suitable for many general-purpose applications.

Cost Comparison: AL1060 < AL3003 < AL5052 < AL6061

If you have other questions about MCPCB, welcome to contact Tammy (Email:sales@bestpcbs.com), she will prove you professional suggestions and solutions.

Posted in mcpcb, Metal Core PCB, PCB News, PCB Technology | No Comments »

ENIG surface finish of FR4 Printed wiring board

November 4th, 2020

Continued to my last blog, do you know why we want to talk more for Gold surface finish of rigid Boards? I would like to take this chance to share more information for the capability from Best Technology.

Electroless nickel immersion gold (ENIG) is a type of surface plating used for printed circuit boards. It consists of an electroless nickel plating covered with a thin layer of immersion gold, which it can protects the nickel from oxidation. It is also used for welding and applied to contacts (such as keys, gold fingers on memory strips, etc
See attached complexity design for ENIG FR4 printed circuit board.

ENIG has several advantages over more conventional (and cheaper) surface plating such as HASL (solder), including excellent surface planarity (particularly helpful for PCBs with large BGA packages), good oxidation resistance, and usability for untreated contact surfaces such as membrane switches and other contact points. See the complex circuit boards design photo.

ENIG also does not wet as evenly or easily as HASL. In addition, ENIG is a costlier finish, but offers the best characteristics for printed circuit boards. The process requires the most steps compared to other common finishing types.
The thickness of Gold Best Technology conforms to IPC Standard IPC-6013.
Let us see the different for gold finish.

Gold-ENIG
The most important factor the gold serves as barrier and protectant to the nickel.
Advantages of ENIG

Immersion finish = excellent flatness
Good for fine pitch / BGA / smaller components from Samtec/Hirose/Molex
Wire bondable
Good heat dissipation
Long shelf Life (12 months in vacuum pack)

Disadvantages of ENIG
Expensive finish
Black Pad/Black Nickel concerns on BGA
Damage from ET (electronics test)
Signal Loss (RF)
Complicated Process

Gold-Hard Gold

Advantages of ENIG
Hard, Durable Surface
No Pb
Long shelf life

Disadvantages of ENIG
Very Expensive
Extra Processing/ Labor Intensive
Use of more solder Resist/Tape
Plating/ Bus Bars
Demarcation(delamination)
Difficulty with other surface finishes.

As an rich experience PCB manufacturer since 2006, Best Technology always improve its Rigid Circuit boards capability to meet customer requirements, If you have any question about the printed circuit boards (PCBs). Warmly welcome to send mail or call Best Tech.

Posted in FR4 PCB, PCB News, PCB Technology | No Comments »

Main types surface finish of FR4 Printed wiring board

November 4th, 2020

Printed Circuit Board surface finish is a coating between bare FR4 board and components. The main function for surface finish is to protect the exposed copper circuitry and provide a solderable surface when assembling（soldering) the components to a copper clad PCB board.

Most of the Rigid Circuit board company can make several different types of surface finish. Best Technology as a leading custom FR4 printed circuit board manufacturer since year 2006, it could provide following different finish.
HASL
Lead-free HASL
Immersion Tin/Immersion Silver
OSP (organic Solderability Preservative)
Gold
ENIG (Electroless Nickel Immersion)
Hard Gold
Wire bonding Gold

As the surface mounts assembly service became more complex and needs to conform to new regulations like RoHS and WEEE. People maybe face the question how to choose a suitable surface finish for your FR4 Copper board?

Before decide to choose suitable surface of copper conductors circuit board, you may need to take the cost, RoHS, your components type, PCB assembly method, factory circuit fabrication capability, and rigid board circuit testability into consideration.
Basis on above information of copper foil PCB, we would like to make a explain PCB finish in detail, wish this may help when you make decision at circuit board design and manufacturing.

HASL/Lead Free HASL
It is a most popular surface finish, and the cost is low and easy to repairable, it is acceptable for simple SMT. But the surface is uneven, it is not suitable for fine pitch components and not good for plated through-hole(PTH). In other way, it is poor wetting.
Material different with same finish
HASL(standard):Typically Tin-Lead
HASL(Lead Free):Typically Tin-copper, Tin-Nickel, without lead
The thickness will conform to IPC 6012 class 2 standard

Advantages of HASL-LF
Excellent solderability
Inexpensive / Low cost
Widely Available and used
Easy reworkable
Allows large processing window
Long industry experience / well known finish

Disadvantages of HASL-LF
Uneven surfaces for printed circuit board
No good for fine pitch components from Samtec/Hirose/Molex
Thermal shock
Solder Bride for circuit board assembly
Plugged or reduced PTH’s
Not suited for < 20mil pitch SMD & BGA
Bridging on fine pitch
Not ideal for HDI products

Immersion Tin

Advantages
Flat surface
No Pb
Good for fine pitch / BGA / smaller components
Mid range cost for lead free finish
Press fit suitable finish
Good solderability after multiple thermal excursions
Easy reworkable

Disadvantages
Very sensitive to handling – gloves must be used
Tin whisker concerns
Aggressive to solder mask – solder mask dam shall be ≥ 5 mil
Not recommended to use peelable masks
Exposed tin on final assembly can corrode
Not good for multiple reflow/assembly process
Difficult to measure thickness

OSP (organic Solderability Preservative)
OSP(organic Solderability Preservative) same with HASL, lower cost but the OSP have flat surface, and it is not good for PTH components, sensitive and short shelf life, it is very easy come to oxidation.

Advantages
Flat surface
No Pb
Good for fine pitch / BGA / smaller components
Inexpensive / Low cost
Easy reworkable
Simple Process
Disadvantages
Not easy to measure thickness
Not good for circuit copper board plated through-hole(PTH)
Short Shelf Life
Maybe cause ICT issue
Exposed Cu on Final assembly
Handling sensitive– gloves must be used and scratches avoided

The above surface finish of Printed Wiring Board compared with Gold finish, the cost is corresponding cheaper, but in my coming blog, I would like mainly to explain Gold finish for printed circuit board fabricator with 13 years rich-experienced in FR4 PCB custom contract manufacturer.

If you have any question about the printed circuit boards (PCBs). Warmly welcome to send mail or call Best Tech.

Posted in FAQ, FR4 PCB, SMT Technology | No Comments »

What is PP (Prepreg) and CORE in a PCB?

October 30th, 2020

We all know that both Prepreg (PP) and CORE are important parts for the printed circuits board. And they are also very common on the PCB structure.

But what exactly they are? What’s the difference of a PP and Core for a FR4 PCB?

Prepreg, referred to as PP, it is a sheet material impregnated with resin and cured to an intermediate level (B-stage), known an insulating material for the PCB board.
As a prepreg material while the PCB production process, before lamination, it is mainly used as an adhesive material and insulating material for the inner conductive pattern of a multilayer PCB.

After the Prepreg is laminated, the semi-cured epoxy resin is squeezed away, starts to flow and solidify, bonding the multilayer circuit boards together, and forming a reliable insulator.

PP, it is placed between the two copper layers to isolate and make the two copper layers adhere. Below picture for you to see where the PP is on a PCB stack up.

And CORE, it is totally different as the Prepreg.

Core is with certain hardness and specified thickness, and with copper foil in both sides.
It is the basic material for making printed circuits boards, and the multilayer PCB board is actually made by pressing Core and Prepreg.
Sometimes, when people are talking about the Copper Clad Laminate (CCL), they also refer to the CORE.

And here is the major difference for the PP and Core:

  1. Prepreg is stayed with a semi-solid material in a PCB, similar to cardboard. But core is different, core is hard, similar to copper;
  2. Prepreg is similar to adhesive + insulator; while Core is the basic material of PCB, they have completely different functions;
  3. PCB Prepreg can curl, but PCB Core cannot bend;
  4. Prepreg is non-conductive, and the core has a copper layer on both sides, which is the conductive medium for a PCB board.

As an PCB manufacturer with more than 15 years experiences in China, Best Technology insists on using the best Copper Clad Laminate ( CCL) materials to make the PCB, no matter Prepreg or CORE, we will select the best FR4 materials for the PCB manufacturing, to make sure all the PCB boards we supplied to customers are with qualified materials and to be your best PCB suppliers in China.

Posted in FR4 PCB, PCB News, PCB Technology | 2 Comments »

What’s the Countersink and counter bore on a PCB drawing?

September 30th, 2020

Firstly, do you know what’s a countersink and counter bore?

By definition, a countersink is a stepped hole, which can allow the fasten parts head to sink fully to the parts.

With counter sink on your design, the tapered head of a screw can sit flush with the top of the laminate, commonly countersink is used to install bolts or other connecting parts.

Below is the example for the hole drawing and picture for a countersink:

Picture: counterbore holes attributes

To drill your countersunk holes accurately in our PCB fabrication plant, the following information is need to be defined when you supply the PCB drawing for us to make the PCB:

  • Which side of the board is the countersink hole should be drilled, on top or bottom?
  • Is the sink and shaft to be through plated or non-plated?
  • Taper angle or countersink angle. 82°, 90°,120° etc.
  • Countersink diameter of top
  • Countersink diameter of bottom (body)
  • Depth of the countersink is to be drilled（the height of the screw to determine the countersink depth.

By comparison, a counterbore makes a flat-bottomed hole and its sides are drilled straight down. This is usually used when a fastener such as a bolt or cap head screw is required to sit flush with or below the level of a surface.

Below is the drawing and picture for a countersink.

Same as the countersink, the counterbore holes attributes drawing is needed to supply with your PCB drawing when fabricate the counterbored holes. But for counterbore on PCB, because the sides of the hole are always parallel, there is no need to specify the angle.

With below drawing, believe it will be more helpful for you to understand the difference for a counter sink hole and counterbore on the printed circuits board.

If need to have any question regarding the counter sunk or counter board on a PCB drawing, please contact us feel free.

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Posted in FR4 PCB, Our News, PCB News, PCB Technology | No Comments »

What are the factors affecting cost of the MCPCB?

September 29th, 2020

Best Technology considers all the factors affecting the cost of MCPCB production while formulating final cost structure. Many customers contact us to know the factors which affecting the price. The factors are Size & Thickness, Number of layers, Cu Thickness, Thermal Conductivity, Surface Finishing etc.

Size & Thickness: Since larger boards require more material.

As you know, 1.6mm is the standard thickness, if you choose non-standar thickness (Thicker or thinner than 1.6mm), sometimes the price will need to increase, it depend on the layers of your MCPCB.

The different number of layers and manufacturer technology：It’s the main factor for affecting the manufacturing price, therefore the circuit board designing is done in such a manner that it comprises a minimum number of circuit layers. 

Thermal Conductivityis one of the most important performances of MCPCB, the higher the thermal conductivity is, the more expensive the price is. At present, the highest thermal conductivity we can provide is 8W/m.K, the commonly used thermal conductivity is 1-3W/m.K

Cu Thickness: The cost will be more expensive if the copper is thicker. We can provide 0.5 OZ, 1.0 OZ, 2.0 OZ, 3.0 OZ, up to 10 OZ.

Surface Finishing: The common Surface Finishing for MCPCB is HASL_LF, OSP  ENIG (The normal thickness of gold is 1u’’). ENIG is more expensive since the gold is expensive and it with good performance for protecting the surface from oxidized.

ENIEPIG is good for wire bonding (the normal thickness of gold is 3uâ€Â).

We always strive to formulate a competitive price structure for our customers, this enables to have a considerable reduction in the total prices and deliver superior quality services to them. If you would like to know more about MCPCB, please directly contact our sales Tammy

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Posted in mcpcb, Metal Core PCB, Our News, PCB News, PCB Technology | No Comments »

What is an HDI FR4 PCB?

September 16th, 2020

HDI abbreviation means High Density Interconnect. HDI PCBs have extremely density trace spaces and lines, micro vias under 0.25mm(10mil), smaller pads and higher connection pad density. See the photo of HDI board laser drill& prepreg thickness ratio.

It is very helpful in enhancing electrical performance and HDI PCB use for high-end products and HDI PCB is regularly used in 4G network communications, medical, Military and Aerospace. See the HDI board which Best Tech made for customers.

HDI PCB is the better option for high-layer count and costly laminated boards. Due to the increasing complexity of design structures laminate, the Blind vias and Buried vias are increasingly used in high-density circuit boards (HDI PCB board). Best Tech always improved manufacture capability for HDI, following production capability of the comparison for 2020 and the capability which Best Tech want to achieve at year 2021.

Following is the advantages to use an HDI PCB

The common reason for using HDI technology is a significant increase in packaging density. In addition, overall space requirements are reduced will result in smaller board sizes and fewer layers. 

1.Denser trace

2.More stable performance

3.Reduce interference inductance and capacitance effects

4.Improve signal integrity in high-speed design

5. Reduce frequent relocation of components

What’s mean for a blind via hole?

It is a hole runs from an outer layer, but not through the entire PCB. These holes can be drilled mechanically or using laser technology.

And what’s mean for a buried via hole?

This is a hole that runs between one or more inner layers. They are normally mechanically drilled.

By the way, we would like to make some explain for the through via hole, see attached photo to know the detail.

Do you want to know the different types for HDI PCB boards?

The following photos mainly shows the different laminate structures available from Best Tech for HDI PCB for prototype and mass production.

What is the minimum pad size of hole on the outer and inner layer?

This is different from manufacturer to manufacturer, but in general you can say that the majority of manufacturers can produce them as follows:
A = 0.10 mm
B = 0.15 mm
C = 0.20 mm

Finally, here is an 8L HDI FR4 PCB which we made for our customer at June. See the stack up information.

Surface finish: ENIG(2uâ€Â)

Features

1. 3+（2）+3  HDI FR4 PCB board

2. L1 L2ã€ÂL2 L3〠L3 L4〠L5 L6〠L6 L7〠L7 L8 laser blind hole, micro via size:0.15mm

3. L3ã€ÂL6 mechanical blind hole, hole size:0.25mm, through hole:0.3mm

4. minimum trace width and space is 3/3mil

5. Finished board thickness: 1.3±10%

6. following is the stack up information

For more information for HDI PCB, welcome to send any query to Best Tech for advice.

Posted in FR4 PCB, HDI PCB, Our News, PCB News, PCB Technology | 1 Comment »

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

September 9th, 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).

It is ideal material for ceramic PCB, lots of engineers want to use it as DBC ceramic PCB substrate.

But it is unfeasible, 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.

Though BeO is unfeasible for DBC technology, but it is feasible for thick film technology.

Because when doing the conductor (Au or AgPd) on BeO substrate, we use silk-screen printing, no need to under high temperature environment, there is no chemical reactions.

Below the manufacturing process for your reference.

Here is the photo of BeO with AgPd conductor.

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Posted in Ceramic PCB, FAQ, Our News, PCB News, PCB Technology | No Comments »

If only the LED pad can be made as SinkPAD?

September 4th, 2020

According to our earlier blogs about SinkPAD introduction,

we can know that the high power LED’s thermal pad can touch the convexity area of copper core directly, so the heat of LED will be dissipated into the air much faster and more efficient than conventional MCPCB, but if only the LED pad can be designed as SinkPAD?

This image has an empty alt attribute; its file name is Stack-up-s.jpg

Actually the pads of other chips or components also can be designed as SinkPAD, one of the most common is the IC pad. In some designs, IC needs to pass through the large current, so it will emit a lot of heat.

This image has an empty alt attribute; its file name is Contrast-images-s.jpg

In order to dissipate heat in time, some customers will directly design the IC solder pad as sinkpad to directly contact the copper base, so that the life cycle will be longer.

As you can see the following picture, it’s the copper layer after doing Etching, the area with blue film we normally named it as convexity, the thermal pad of IC will touch the convexity directly to achieve the purpose of dissipating the heat very fast.

This image has an empty alt attribute; its file name is Convexity-s.jpg

If you have other questions about SinkPAD, welcome to contact Tammy (Email:sales9@www.bestpcbs.com), she will prove you professional suggestions and solutions.

In the end, I’d like to share the manufacturing process of SinkPAD Board with you, please Click here: SinkPAD-Board-Manufacturing-Process-Best-Technology.pdf

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Posted in Metal Core PCB, PCB News, PCB Technology, SinkPAD | No Comments »

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