Q: Drilling Hole for Different Layers Connection

Drilling Hole for Different Layers Connection After lamination, the inner layer is done. What follows next is to drill hole for connection of trace in different layers and also those components holes that will be mounted when assembly. To program the drilling machine as per PCB data from the OP, the drilling hole process begins. Drill Process After the drilling hole process is all done, it is all ready for the next PTH copper plating process.

Question 1

What is impedance control? - Part.3

Accepted Answer

The impedance of the PCB trace will be determined by its resistance, inductance and conductance. The PCB impedance ranges from 25 to 120 ohm. The main factors that affect the impedance of the PCB traces are as below:

1. Trace width / thickness;
2. The dielectric constant;
3. Thickness of the medium;
4. The thickness of the pad;
5. The path of the ground line;
6. The traces around the trace

PCB transmission lines usually consist of traces, one or more reference layers, and insulating materials. Traces and slabs constitute the control impedance.

Question 2

Introduce COB's bonding wire and its pulling force

Accepted Answer

The previous article has introduced what COB is and the process of COB. Under the process, what kind of bonding wire and tensile test does COB have?
After the COB die is adhered and baked, the wire bonding process is followed. The COB process is different from IC packaging. It is gold wire for IC, and aluminum wire for COB. Therefore, the shape of the solder joint will be different, and secondly, the tensile force of the solder wire will also be different.

Wire Bonding

According to the shape of the solder joint, the wire bonding process can be divided into two types: "Ball Bond" and "Wedge Bond". COB usually uses aluminum wire (Al wire) so it will be Wedge Bond. However, according to experience and data, the strength of ball welding is better than that of wedge welding, but the "gold wire" is also more expensive.

Wire Pull Test

In the IC packaging process, the quality of the bonding wire is usually judged by three methods: Wire pull, die shift, and Ball Shift. Generally speaking, most COB The manufacturing process will only test the wire tension, which can measure whether the strength of the solder joints on the PCB is sufficient. The COB wire tension requirement is usually only greater than 3g according to the IPC specification (TM-650 2.4.42.3).

Question 3

Where are printed circuit boards used? VI

Accepted Answer

PCBs are used in many different sectors. Today we are talking about some applications in industrial products. PCB are widely used in the industrial part.

The PCBs used in the industrial sector often need to be especially high-powered and be durable enough to withstand the harsh conditions that exist in industrial facilities. PCBs may need to be resistant to rough handling, vibrating machinery, extreme temperatures or harsh chemicals. To meet this need for durability, industrial PCBs may be made with durable metals or thermal-resistant materials and be thicker than other kinds of PCBs.

Manufacturing equipment
Power equipment
Measuring equipment

*Related Article:
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Where are printed circuit boards used? II
Where are printed circuit boards used? III
Where are printed circuit boards used? IV
Where are printed circuit boards used? V

Question 4

Panel Copper Plating → PTH (Plated Through Hole)

Accepted Answer

The step follows drilling hole is copper plating.
Except those drilling holes for tooling purpose, the rest of the drilling-hole wall will be plated with copper as for the purpose of connection of trace in different layers or for those DIP components.

By blocking the holes and areas with no needs of copper, copper plating is applied not only on the drilling-hole wall but also on the whole PCB.
For requirement of finished 70um, normally PCB vendor takes 35um material and do copper plating to be 70um.

Question 5

What is E-TEST?

Accepted Answer

How does PCB manufacturer ensure the bare PCB is within standard before delivery?

Once of tests it will be conducted is “E-test” which is also known as electricity test. The main purpose of E-test is to make sure there’s no open circuit and short circuit.

When it’s sample production, most of time the manufacturer will use “Flying Probe test” for E-TEST. Even though flying probe test is comparatively time consuming in terms of production efficiency but it makes sense especially the project is still on pilot phase.

Once the project enters Mass Production, usually the PCB manufacturer will produce specialized tooling for each project. No matter it’s “Flying probe test” or “tooling test”, the main target is to detect NG circuit during “E-TEST STAGE” and ensure the quality is within client’s standard.

What is HiPot test?

Question 6

What is impedance control? - Part.2

Accepted Answer

Last time we have briefly introduced the PCB data transmission and impedance control. And the transmission method can be divided in two types – Single-ended and Differential signal. Both have their own pros & cons, and which method to use for transmission depends on the functionality of the IC as well as electrical considerations. Nowadays, differential transmission has become the mainstream of high-speed transmission.

What is Single-Ended Signal
Single-ended signals generally refer to all kinds of signals that can transmit messages with one transmission trace (signals on PCB are mostly this kind). Its biggest pro is that the impedance is easy to control.

What is Differential Signal

Differential signals use two single-ended signal traces (Positive and Negative ) to transmit signals at the same time. These two signals should have two features:
1. Same voltage amplitude
2. The phase of the signal is opposite, that is, one positive and one negative.

What is impedance control? - Part.1

Question 7

What is Glass Transition Temperature, also known as TG?

Accepted Answer

Sometimes you can see TG150/TG170, etc. on the PCB material. What does this TG mean?

TG(Glass Transition Temperature) is one of the most important characteristics of all plastic and epoxy resin materials. In fact, TG(Glass Transition Temperature) value is also one of the quality indicators of glass fiber for PCB.
When the temperature is lower than the glass transition temperature (TG), the plastic enters glassy state which is rigid but with brittle characteristics. Just like the characteristics of glass, it is hard but easily brittle.
When the temperature is higher than the glass transition temperature (TG), the plastic parts will show a soft and flexible rubbery state. Therefore, the glass transition temperature (TG) is generally the temperature at which the plastics undergo a phase transition from the glassy state to the rubber state.

As PCB’s TG(Glass Transition Temperature) increasing, the heat resistance, moisture resistance, chemical resistance, and resistance stability characteristics of PCB prodution will be strengthened and improved. The higher the TG(Glass Transition Temperature) value, the higher temperature PCB can endure, especially in the lead-free manufacturing process, where there are more applications of high TG(Glass Transition Temperature).

High TG(Glass Transition Temperature) refers to high heat resistance. The development of high functionalization and high multi-layering requires higher heat resistance of PCB substrate materials as an important guarantee. The emergence and development of high-density mounting technologies represented by SMT and CMT have made PCBs increasingly require specifications with high heat resistance of substrates in terms of small apertures, fine lines, and thinning.

Thus, regards PCB production, the difference between FR-4 and high TG FR-4 is that in a high temperature state, especially when heated after moisture absorption, the material’s mechanical strength, dimensional stability, adhesiveness, water absorption, thermal decomposition, and thermal expansion.

Question 8

Where are printed circuit boards used? V

Accepted Answer

Today we are talking about some applications in military products. Military-grade PCBs carry stringent performance, sourcing, and manufacturing requirements that are encoded in a number of standards, such as IPC-A-610E Class 3, MIL-PRF-31032, MIL-PRF-55110, etc. These standards specify performance requirements for high-performance electronic products.

These military printed circuit boards will often be subjected to high pressures and stresses, meaning they will frequently require high-temperature substrates like temperature-resistant laminates, copper or aluminum. Military PCB manufacturers must produce PCBs that will resist heat-induced oxidation and effectively dissipate heat in a low-weight design.

• Auxiliary power units for radar control systems
• Radio communications systems
• Control tower systems
• LED lighting systems
• Underwater navigation systems
• Jet instrumentation
• Jamming systems

*Related Article:
Where are printed circuit boards used?
Where are printed circuit boards used? II
Where are printed circuit boards used? III
Where are printed circuit boards used? IV

Question 9

Final step before PCB delivery for International shipment – Standard Packing Procedure at ExPlus

Accepted Answer

«Standard Packing Procedure at ExPlus»

After the PCB passed FQC inspection and OQC inspector confirmed O.K., the PCB will be transferred to the warehouse and waiting for packing. When the packing staff receive PCB, he or she will first check the part number and OP, and then follow client requirements if there’s any for packing.

«Reduce potential risks during International transportation»

Different from domestic delivery, the PCB manufacturer shall consider all kinds of risk such as bumpy, falling and so on during international shipping. To reduce the risk of PCB damage due to transportation, ExPlus’ standard packing procedure will be following. First, the carton shall be multiple layers waterproof carton. Second, before place PCB into the carton, the packing staff will put buffer packaging materials(at ExPlus we use wave board as below image shows) on the bottom of carton and then surround the PCB with more wave boards for protection. Once the packing staff ensure the board won’t slide due to any movement, he or she could seal the box and measure the weight. For safety concern, the Net weight of each carton won’t exceed 20 k.g.. On outside of carton, the details including part number, PO, D/C, quantity and weight shall be listed. Once the box is sealed, it’s all ready to go.

ExPlus package

Question 10

Drilling Hole for Different Layers Connection

Accepted Answer

Drilling Hole for Different Layers Connection

After lamination, the inner layer is done.

What follows next is to drill hole for connection of trace in different layers and also those components holes that will be mounted when assembly.

To program the drilling machine as per PCB data from the OP, the drilling hole process begins.

Drill Process

After the drilling hole process is all done, it is all ready for the next PTH copper plating process.

Drilling Hole for Different Layers Connection

Knowledge