Working temperature changes can have a significant influence on the operation, reliability, lifetime and quality of products. Temperature rises results in materials expanding, however, the substrate materials that PCB are made of have different thermal expansion coefficients, this causes mechanical stress that can create micro-cracks that may be undetected during electrical tests carried out at the end of production.
Due to the policy of RoHS issued in 2002 required lead-free alloys for soldering. However, removing lead directly results in the rise of melting temperature, printed circuit boards are therefore subject to higher temperatures during soldering (including reflow and wave). Depending on the chosen reflow process (single, double…), it is necessary to use a PCB with appropriate mechanical characteristics, especially one with suitable Tg.Â
What is Tg?
Tg (glass transition temperature) is the temperature value that guarantees the mechanical stability of the PCB during operational life time of the PCB, it refers to the critical temperature at which the substrate melts from solid to rubberized liquid, we called the Tg point, or melting point for easy to understanding. The higher the Tg point is, the higher the temperature requirement of the board will be when laminated, and high Tg board after laminated will also be hard and brittle, which benefits for next process such as mechanical drilling (if any) and keep better electrical properties during use.
The glass transition temperature is hard to be measured accurately in considerate many of factors, as well as each material have its own molecular structure, therefore, different materials have a different glass transition temperature, and two different materials may have the same Tg value even they have different characteristics, this enable us to have an alternative choice when the needed material is out of stock.
Features of High Tg materials
Better thermal stability
Good resistance to moisture
Lower thermal expansion coefficient
Good chemical resistance than low Tg material
High value of thermal stress resistance
Excellent reliability
Advantages of High Tg PCB
In general, a normal PCB FR4-Tg is 130-140 degrees, the medium Tg is greater than 150-160 degrees, and high Tg is greater than 170 degrees, High FR4-Tg will have better mechanical and chemical resistance to heat and moisture than standard FR4, here are some advantages of high Tg PCB for your reviewing:
Higher stability: It will automatically improve the heat resistance, chemical resistance, moisture resistance, as well as stability of the device if increasing the Tg of a PCB substrate.
Withstand high power density design: If the device has a high power density and a fairly high calorific value, then high Tg PCB will be a good solution for heat management.
Larger printed circuit boards can be used to change the design and power requirements of the equipment while reducing the heat generation of ordinary boards, and high Tg PCBS can also be used.
Ideal choice of multi-layer and HDI PCB: Because multi-layer and HDI PCB are more compact and circuit dense, it will result in a high level of heat dissipation. Therefore, high TG PCBs are commonly used in multi-layer and HDI PCBs to ensure the reliability of PCB manufacturing.
When do you need a High Tg PCB?
Normally to ensure the best performance of a PCB, the maximum operating temperature of the circuit board should be about 20 degrees less than the glass transition temperature. For example, if the Tg value of material is 150 degrees, then the actual operating temperature of this circuit board shouldn’t more than 130 degrees. So, when do you need a high Tg PCB?
If your end application requires to bear a thermal load greater than 25 degrees centigrade below the Tg, then a high Tg PCB is the best choice for your needs.
To make sure the safety when your products require an operating temperature equal or greater than 130 degrees, a high Tg PCB is great for your application.
If your application requires a multi-layer PCB to meet your needs, then a high Tg material is good for the PCB.
Applications that require a high Tg PCB
Gateway
Inverter
Antenna
Wifi Booster
Embedded Systems Development
Embedded Computer Systems
Ac Power Supplies
RF device
LED industry
Best Tech has rich experience in manufacturing High Tg PCB, we can make PCBs from Tg170 to maximum Tg260, meanwhile, if your application need to use under extremely high temperature like 800C, you’d better use Ceramic board which can go through -55~880C.
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 Resistance
0.1 Ohms
Maximum Test Voltage
1000 Volts
Max Isolated Resistance
25 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.
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.
What are the IPC Standards for?
Before we can understand IPC standards, we first need to know who made them. It comes from the IPC Association, a trade association whose goal is to standardize assembly and production requirements for electronic devices and components. It was founded in 1957 as the Printed Circuit Research Institute. Its name was later changed to the Institute for Electronic Circuit Interconnection and Packaging to highlight the expansion from bare boards to packages and electronic components. In 1999, the organization officially changed its name to IPC with the slogan “Association Connecting Electronics Industries”.
IPC standards are the most widely recognized code of acceptability in the electronics industry. The organization publishes standards for nearly every stage of the electronic product development cycle, including design, procurement, assembly, packaging, and more. In other words, IPC standards refer to everything in the electronics industry and are the basic knowledge of designers and manufacturers.
Just like the IPC standards tree, there are many different aspects of standards that all serve the end product. IPC-A-610, for example, focuses on the acceptability of electronic components and is used worldwide by original equipment manufacturers and EMS companies.
What is the PCB IPC Standard?
IPC plays a vital role in the PCB industry by establishing standards that cover every stage of PCB production from design to manufacturing. These standards ensure consistency and compatibility throughout the PCB process. During the design phase, IPC standards guide file formats, PCB design software, design guidelines, and electronic product documentation. They also affect the material selection of PCB components, surface mount equipment and surface treatments. In addition, these standards are essential for testing and evaluating the acceptability of printed boards.
When it comes to welding, IPC standards cover a variety of techniques, including reflow soldering, wave soldering and welding. These guidelines help companies determine whether their electrical and electronic components meet quality expectations during manufacturing. IPC standards also address cable and harness assemblies to ensure they meet standards.
The most widely recognized IPC standard for PCBs is IPC-6011, which Outlines the performance requirements for PCBS. However, IPC-6012 is more specific and governs the qualification and performance of rigid PCBs. IPC-6012 covers everything from how the PCB should be made to its thickness and the integrity of the copper layer. Compliance with this standard ensures that PCBs meet electrical and mechanical performance expectations. Whether you’re creating boards for high-end computers or small consumer devices, compliance with PCB IPC standards is critical to meeting industry and customer expectations. Here is the IPC tree for your reference:
What is the IPC Level of PCB?
One of the most widely used industry standards in the manufacturing of printed circuit boards is IPC-A-610C Acceptability of Electronic Assemblies and 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.
For PCB manufacturing, do you know which IPC standards are commonly used?
multilayer pcb
IPC Standard for PCBs
The IPC has created several standards for printed circuit board (PCB) design, manufacturing, and assembly. Here I would like to share you some standards which we mainly use:
IPC-2221
A general standard that covers almost every aspect of PCB design, including electrical considerations, thermal design, and manufacturing-ready design.
IPC-2222
A guide for rigid PCB cross-sectional design, including recommendations for board thickness, hole aspect ratio, and dielectric clearance.
IPC-2223
A standard for reliable Flex-PCB design, including guidelines for material selection, impedance control, and pad placement.
IPC-2224
A standard for PC card form PCBs, including design requirements for organic and inorganic materials, and single, double, or multilayered interconnections.
IPC-A-610
A standard for PCB assembly that classifies PCBs into three quality levels, with Class 1 being the lowest and Class 3 being the highest.
IPC-6011
General Performance Specification for Printed Boards
IPC-6012
Appraisal performance and specifications for Rigid printed boards
IPC-6013
Appraisal performance and specifications for Flexible printed boards
Appraisal and performance of permanent performance
IPC-HM-860
Multilayer Hybrid Circuit Specification
J-STD-003
Solderable test for printed boards
IPC-A-600F
Acceptance conditions for printed boards
IPC-4761
Design Guide for Protection of Printed Board Via Structure
resin filled production bpm20599
What is IPC-A-610 Standard?
IPC-A-610 Standard is one of the most widely recognized standards in the electronics industry, specifically focusing on the acceptability of electronic assemblies. It provides detailed guidelines and criteria for the inspection of PCB assemblies, so that these assemblies meet the necessary quality levels for their intended use. Its main content includes:
1. Soldering Criteria
IPC-A-610 provides in-depth guidelines on acceptable soldering techniques, covering solder joints, surface mount devices (SMDs), through-hole components, and wire terminations. It explains what constitutes an acceptable versus defective solder joint, ensuring that the electrical connections are reliable.
2. Component Placement
The standard includes criteria for the correct placement and alignment of electronic components on PCBs. It specifies the acceptable tolerances for misalignment and ensures components are correctly placed for proper electrical performance and physical integrity.
3. PCB Assembly Defects
IPC-A-610 details different types of assembly defects, such as insufficient solder, tombstoning, lifted pads, and more. Each defect is categorized based on its severity and impact on the function and reliability of the product, providing guidance on whether a defect can be accepted or if it requires rework.
4. Classes of Electronic Assemblies
The standard divides electronic assemblies into three classes based on the end-use of the product:
Class 1 – General electronic products
Class 2 – Dedicated service electronic products
Class 3 – High-performance products
5. Mechanical Assembly
IPC-A-610 provides criteria for the mechanical aspects of PCB assemblies, such as mounting hardware, screws, connectors, and wire routing.
6. Coating and Potting
The standard covers the application of protective coatings (conformal coatings) and potting materials that protect the PCB from environmental damage such as moisture, dust, or chemicals. It specifies acceptable thicknesses, coverage areas, and inspection methods.
7. Cleaning Requirements
The cleanliness of PCB assemblies is critical for preventing performance degradation over time. IPC-A-610 outlines acceptable levels of residues from fluxes and other contaminants and specifies methods for inspecting and verifying cleanliness.
8. Cable and Wire Harness Assemblies
The standard includes requirements for assembling and inspecting cable and wire harnesses.
9. Solderless Wire Wraps
The standard also touches on solderless wire-wrapped connections, which are used in some applications where soldering is not practical or preferred. IPC-A-610 defines the acceptable criteria for such connections.
10. Inspection and Testing
The IPC-A-610 standard provides guidelines for visual inspection and testing methods used to evaluate whether an assembly meets the required acceptability criteria. This can include both automated and manual inspection processes, depending on the class of product.
Why IPC Standard is Important?
IPC standards are of great importance to the circuit board industry.
1. IPC standard specifies the requirements for all aspects of the design, manufacturing and assembly of the circuit board, including material selection, size specifications, welding quality, reliability testing, etc., providing a unified reference and guide for circuit board manufacturers to improve product quality and reliability.
2. IPC standards can help communicate and cooperate between PCB manufacturers and customers. By referring to IPC standards, the two parties can reach a consensus on PCB specifications, quality requirements and other aspects, reduce misunderstandings and disputes, and improve production efficiency.
3. For customers, IPC standards provide confidence. When a company adheres to these standards, they can trust that the final product will be reliable and durable, even in demanding environments.
4. In addition, IPC standards also contribute to the technological innovation and development of the circuit board manufacturing industry. By being in line with international standards and understanding the latest technological trends and standard requirements, manufacturers can continuously improve production processes and equipment, improve production efficiency and product quality, and enhance competitiveness.
At the same time, IPC regularly updates and revises standards to meet changing technology and market needs.
What is the IPC Standard for PCB Clearance?
PCB clearance, or the distance between conductive components, is essential to avoid electrical shorts or interference. Without proper clearance, electrical shorts could occur, potentially leading to device failure or safety hazards. The IPC-2221 standard covers PCB design and provides guidelines for this clearance, ensuring safety and functionality. This standard specifies how much space is needed between traces, pads, and other conductive materials depending on the operating voltage. However, the minimum clearance between any two conductors on a PCB depends on the device’s intended use and voltage:
General-purpose devices:Â 0.1 mm (4 mils)Â
Power conversion devices:Â 0.13 mm (5.1 mils)Â
Class 2 and 3 PCBs:Â 0.25 mm (10 mils) for low voltage and 0.5 mm (20 mils) for high voltageÂ
What are the IPC Standards for PCB Repair?
PCB repair can be tricky, but IPC-7711/7721 offers guidance on how to properly rework and repair PCBs. These standards provide detailed procedures for everything from removing defective components to repairing damaged traces and soldering issues.
By following IPC-7711/7721, technicians can restore a PCB to its original condition without compromising its performance. This is critical in industries where PCBs are expensive or difficult to replace, such as aerospace and medical devices. Repair standards also reduce the environmental impact by extending the life of the PCB, making repairs more sustainable.
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.
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.
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.
If you work in Printed Circuit Board industry, you may know a normal PCB FR4-Tg is 130-140 degrees, the medium Tg is greater than 150-160 degrees, and High-TG FR4 Printed Circuit Board is greater than 170 degrees. And what is a High-TG FR4 Printed Circuit Board? High-TG PCB is another name for a high-temperature FR4 PCB, it means the printed wiring boards designed to endure for extremely high-temperature. A Printed Circuit Board is defined as high-TG FR4 PCB if its glass transition temperature (TG) is higher than 170 degrees Celsius. High-TG FR4 will have better mechanical and chemical resistance to heat and moisture than standard FR4. The higher the TG value, the better the temperature resistance of the material, so High-TG FR4 is more and more popular particularly working in high power industry. Best Technology can provide many different High-TG FR4 material for Rigid Circuit board, Typical High-TG FR4 PCB material including: ITEQ-IT-180A, ISOLA 370HR, ShengYi S1000-2 and etc.
Part of the inventory of raw material-1
Part of the inventory of raw material-2
Part of the inventory of raw material-3
From the following PCB picture, you can see the normal TG130 FR4 PCB substrate is not only softening, deformation, melting, as well as other phenomenon working under high temperatures, but also there is a sharp decline in electrical properties, which will effect on product life.
Solder mask blistering-1
ã€ÂSolder mask blistering-2
If your FR4 Printed Circuit Board or PCBA board appear to above problems, then you should consider to use a High-TG FR4 Rigid Circuit Board. it may be catching your interest willing to understand a little bit more about High-TG FR4 printed circuit boards. Because High Tg Rigid Circuit board have a better stability at high temperatures, the substrate provides better heat resistance, mechanical and chemical stability for the circuit board.
BPM20396)
Properties/ Applications of high Tg PCB With the rapid development of electronics industry, High-TG FR4 PCB is widely used in Uninterrupted Power Supply, precise instrument as well as industry. High-TG FR4 PCB material probably designed for the high functionality, high multi-layer development high-density circuit; higher heat resistance and high-density surface mounting technology (SMT). So, the demand on High-TG FR4 PCB material become more widely used PCB manufacturing. What’s more, High TG material is also popular in LED lighting industry, because heat dissipation of LED is higher than normal electronic components, but same structure of FR-4 board is much cheaper than metal core PCB, such as aluminum PCB. High-TG FR4 PCB materials have the following properties:  Resistance to high temperatures  Long delamination durability (aging of materials to consider for safety reasons)  Low thermal expansion Excellent PTH reliability Good mechanical properties High temperature durability High value of thermal stress resistance high temperature durability long delamination durability Low Z axis expansion (CTE)
BPM19308
Advantages of High-TG FR4 PCB Higher stability: it will automatically improve the heat resistance, chemical resistance, moisture resistance, as well as stability of the device if increasing the TG of a printed circuit board substrate. Bear high power density designs: high TG PCB will be a good solution for heat management if the device has high power density with quite high heat generation rate. It can achieve with using a larger printed circuit board to change the design and power requirements of a device when reducing the heat generation of ordinary board, what’s more, it also can use the high TG PCB. Ideal for multilayer & HDI PCBs: there will lead to high levels of heat dissipation because multilayer & HDI PCBs are more compact and have dense circuits. So high TG PCBs are often used for the multilayer & HDI PCBs so that it can make sure reliability in Printed circuit board fabrication.
BPM20005 TOP
BPM20005 BOT
If your applications are in any danger of subjecting your PCBs to extreme temperatures or the PCB is required to be RoHS Compliant, it will be in your best interest to look into high-TG FR4 PCBs. Come to contact Best Technology Co., Limited. for High-TG PCB assistance. we can help you determine if you need high-temperature printed circuit boards and direct you to which specific boards are likely to be useful for your design and application. If you are transitioning to RoHS or just need more information about the High TG laminates, just give us a call and we’ll be happy to accommodate you. contact us online right now.
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.
