1. PCB material currently used by MITAC

A. Urea cardboard

The characteristic is that the color is light yellow, and it is often used for single panel.

B. CAM-3 board

Features: ﹕ color is milky white, good toughness, high CTI (600V), carbon dioxide emissions are only a quarter of normal It is now more commonly used for single panels.

C. FR4 fiberboard

Features: Made of fiber, good toughness, filaments pull each other when broken, often used for multi-panel, and its thermal expansion coefficient is 13 (16ppm / c). The motherboard used by our factory is made of this board.

D. Multilayer boards

Characteristics: ﹕ High Tg, high heat resistance and low thermal expansion, low dielectric constant and dielectric loss materials, mostly used in four or more layers﹒

E. Soft board

Features: ﹕ material is soft and transparent, often used at the electrical connection of two boards, easy to fold﹒ For example, the connection between the LCD and the computer body in a laptop.

F. Other

With personal computers﹒ With the popularity of multimedia digital information terminal products such as mobile phones, PCBs have also become lighter, thinner, shorter, and smaller. Some large group companies abroad have developed more PCB sheets, such as halogen-free, antimony-free environmentally friendly products, high heat resistance, high Tg sheet, low thermal expansion coefficient, low dielectric constant, and low dielectric loss sheet. Its representative products are ﹕ FR-5, Tg200 board, PEE board, PI board, CEL-475, etc .﹒ It’s just not popular in China now.

2. The current MITAC PCB-Layout process

A﹒ R & D provides SCHMATIC (EE), FAB OUTLINE (ME) product research and development department provides us with schematic diagrams, mechanical engineers provide us with peripheral information﹒

B﹒ Create new part

We call out parts from LIBRARIAN according to the schematic diagram. If there is no such part in LIBRARIAN, we will create a new part.

C﹒ Part layout

After the parts are complete, we need to layout the parts.

D﹒ ROUTING routing

This is our main task, we will carry out the routing after the game is set.

E﹒ Final finishing

After ROUTING, we will use FABLINK to finally sort out all the information we need

F﹒ GERBER

GERBER files needed by PC board manufacturers

G﹒ Data saving

After all the work is done, save the data for easy modification and verification later

3. Some basic terms about printing plates

On the insulating substrate, a conductive pattern made of printed wiring, printed components, or a combination of them is called a printed circuit according to a predetermined design. A conductive pattern that provides electrical connections between components on an insulating substrate, called a printed circuit. It does not include printing components. The finished board of printed circuit or printed wiring is called printed circuit board or printed circuit board, also known as printed board. Printed boards can be divided into two categories according to whether the substrate used is rigid or flexible: rigid printed board brushes and flexible printed boards. Rigid-flexible printed boards have also appeared this year. According to the number of layers of the conductor pattern, it can be divided into single-sided, double-sided, and multilayer printed boards. The entire outer surface of the conductor pattern is on the same plane as the substrate surface. Printing plate, called flat printing plate.

After the electronic equipment uses printed boards, due to the consistency of similar printed boards, errors in manual wiring are avoided, and automatic insertion or placement of electronic components, automatic soldering, and automatic detection can be achieved to ensure the quality of electronic equipment and improve It improves labor productivity, reduces costs, and facilitates maintenance. Printed boards have evolved from single-layer to double-sided, multi-layer and flexible, and still maintain their respective development trends. Due to the continuous trend towards high precision, high density and high reliability The development direction continues to reduce the volume and reduce the cost, so that the printed board will still maintain a strong vitality in the future development of electronic equipment.

4. V-1 grade FR-4?   

FR-4 (flame-resistant laminated sheet) is made of “glass fiber cloth”, impregnated with liquid flame-resistant “epoxy resin” as a binder, and then laminated into sheets of various thicknesses. The so-called V-1 refers to a sample of copper-free glass-fiber epoxy resin substrate that is 0.5 inches wide, 5 inches long, and free of thickness. After burning on a specific flame at an oblique direction of 45 °, the fire source is removed and Measure the number of seconds of delayed burning, and wait for it to burn off after all. After ten consecutive test firings, those with a total delayed firing time of less than 250 seconds are referred to as V-1 FR-4, and those with less than 50 seconds are referred to as V-0 FR-4.

5. A brief history of PCB development

The basic concepts of printed circuits have been proposed in patents at the beginning of this century. In 1947, the first technical seminar on printed circuits was initiated by the NASA and the American Bureau of Standards. At that time, 26 different printed circuit manufacturing methods were listed. It can be summarized into six types: ﹕ coating method, spraying method, chemical deposition method, vacuum evaporation method, molding method and powder pressing method. At the time, these methods failed to achieve large-scale industrial production. Until the early 1950s, due to copper foil and layer The problem of bonding the pressure plate was solved, the performance of the copper-clad laminate was stable and reliable, and large-scale industrial production was achieved. The copper foil etching method has become the mainstream of printed board manufacturing technology and has been developed to this day. Large-scale production of surface printing and multi-layer printed boards was realized.Due to the rapid development of large-scale integrated circuits and electronic calculators in the 1970s, the rapid development of surface mount technology in the 1980s and multi-chip assembly technology in the 1990s promoted printing. The continuous advancement of circuit board production technology, a batch of new materials, new equipment, and new test equipment have emerged one after another, and the printed circuit production technology has further developed in the direction of high density, thin wires, multiple layers, high reliability, low cost and automated continuous production. .

6. Schematic design process

The generation of a schematic diagram is generally considered as the first step in the PCB production process.It is also a specific realization of the product envisioned by the electronics engineering technicians.It is composed of many logic components (such as gate circuits, resistors, capacitors, etc. of various ICs). ) Is composed of different logical connections. To make a schematic diagram, the source of its logical components is that some CAD software contains a large library of logical components (such as TANGO PADS, etc.) and some CAD software in addition to the logic

In addition to the editing component library, users can also add and build new logic components (such as Cadence, Mentor, Zuken, etc.), and users can use these logic components to implement the logical function of the product to be designed.

1 Building logical components

A logic component is a component that provides a logic function (such as an LSOO gate, a flip-flop, or an ASIC circuit).

1) Definition of logical component model (or component name).

2) Package form of logic component pins

3) Description of logic component pins

4) Definition of the shape and symbol size of logic components

2 Functional characteristics of logic components

To simulate the logic circuit, it is necessary to describe the functional characteristics of each logic component, such as the timing relationship of the logic components, the initial rising edge (RISE), falling edge (FALL), delay time, and drive attenuation. Decay time, etc.

3 Notes on the logic component library

Because there are many logic components, all of them are built in a library, which is easy to cause confusion and difficult to manage.Therefore, logic components with similar functional characteristics are generally placed in a library and managed according to functional characteristics, such as A / D, D / A conversion devices. CMOS devices, storage devices, TTL devices, linear devices, op amp devices, comparison devices, etc. are all placed under the same library. It can also be classified according to company manufacturers such as: MOTOROLA, NEC, INTEL, etc.

7. The function of printed circuits in electronic equipment

(1) Provide mechanical support for fixing and assembling various electronic components such as integrated circuits.

(2) Wiring and electrical connection or electrical insulation between various electronic components such as integrated circuits.

(3) Provide the required electrical characteristics, such as characteristic impedance.

(4) Provide solder mask graphics for automatic soldering, and provide identifiers and graphics for component insertion, inspection, and maintenance.

8.How will PCB manufacturing technology change to meet environmental protection requirements?

1) Reduce lead content   

The method of making pattern plating with electroplated lead-tin is rapidly being abolished. In the future, there will be more conversion to the process of panel plating (also known as panel plating). In the case of graphic plating, tin plating will also become mainstream. Where solder is used, the solder will be converted to a lead-free material, and there will be greater progress in this area in the future﹒ It is expected that the impact of this transition on the entire PCB manufacturing process will be small.

(2) Reduce the use of formaldehyde   

Formaldehyde is used as a reducing agent for electroless copper plating (also known as electroless copper plating, electroless copper plating) in the production of PCBs. From the perspective of environmental protection, the use of it will be more strictly limited in the future. In the future, through the change of the plating process, reducing or no longer using formaldehyde materials will be the future development trend. Direct plating will become a widely used plating method. The re-understanding of the significance of using this plating method and the further improvement of this process method are important tasks that need to be carried out in the future.

(3) Progress of MID   

Thermoplastic resin is a polymer material that can be easily recycled. In order to meet the requirements of environmental protection and ecological environment protection in the future, more thermoplastic resins will be used in circuit components in the future. It is called ﹕ Molded Interconnect Device (MID), which will replace some traditional manufacturing technology PCB﹒ MID will become a “new army” with development potential in PCB﹒

(4) other materials   

Materials that are compatible with environmental protection, such as solder resist materials, printed circuit board substrate materials (flame-retardant non-halogen-containing substrates), will be developed more quickly. This also makes major changes in the main materials used in the PCB manufacturing process. For this reason, in PCB manufacturing, those original process technologies will be greatly affected.

9. High-speed circuit

 It is generally believed that if the frequency of a digital logic circuit reaches or exceeds 45MHZ ~ 50MHZ, and the circuit working above this frequency has already occupied a certain amount of the entire electronic system (say 1/3), it is called a high speed circuit.

In fact, the harmonic frequency of the signal edge is higher than the frequency of the signal itself, which is the unexpected result of the signal transmission caused by the rapidly changing rising and falling edges (or signal transitions) of the signal. Therefore, it is generally agreed that if the line propagation delay is greater than the rise time of the driving end of the digital signal, such signals are considered to be high-speed signals and produce transmission line effects. The transmission of a signal occurs at a moment when the state of the signal changes, such as the rise or fall time. The signal passes a fixed time from the driver to the receiver. If the transmission time is less than 1/2 of the rise or fall time, the reflected signal from the receiver will reach the driver before the signal changes state. Conversely, the reflected signal will reach the driver after the signal changes state. If the reflected signal is strong, the superimposed waveform may change the logic state.

10. V_CUT   

One method of forming a circuit board is to cut straight lines at the same position on the upper and lower sides of the board without cutting them, so that the grooves forming a V-shape can be broken manually or by using a jig. V_CUT

11. Gold Fingers   

Refers to certain circuit boards_ such as network cards, the gold-plated wires on the upper side of the upper panel are called gold fingers because their shapes are similar to fingers