"What is PCB?
PCB (Printed Circuit Board is a most common name, or "Printed Wiring Boards" or "Printed Wiring Cards". The circuit is composed of the wiring of the point to the point before the PCB appears. This method is very reliable, because with the aging of the circuit, the rupture of the line can cause the circuit node to open or short the circuit.
Winding technology is a major advancement of circuit technology, which enhances the durability of the line and replaceability by wreathes the small-diameter wire onto the pillar of the connection point.
(1977 Z80 computer winding backplane)
When the electronics industry develops from vacuum tubes, relays to silicon semiconductors and integrated circuits, the size and price of electronic components are also declining. Electronic products have become more frequent in the consumption field, which promotes manufacturers to find smaller and cost-effective programs. So, the PCB was born.
Composition
The PCB looks like a multi-layer cake or a thousand-level-fabrication of the layer of different materials, and is pressed together by heat and adhesive.
Start with the intermediate layer.
FR
The substrate of the PCB is generally glass fibers. In most cases, the glass fiber substrate of the PCB generally refers to "" FR4 "". "FR4" "This solid material gives PCB hardness and thickness. In addition to this substrate of FR4, there is a flexible circuit board produced by flexible high temperature plastic (polyimide or similar).
You may find a PCB with different thicknesses; however, the thickness of SparkFun's thickness is 1.6 mm (0.063 ''). Some products have also used other thicknesses, such as LilyPad, ARUDINO PRO Micro Boards adopts 0.8 mm thick.
Cheap PCB and cave plates (see the figure below) are made of materials such as epoxy or phenol, lack of FR4 durability, but it is much cheaper. When welding things on this board, a large odor will be smelling. This type of substrate is often used inside very low-end consumer goods. The phenolic substance has a lower thermal decomposition temperature, and the welding time can cause its decomposition carbonization, and exude a unpleasant taste.
Copper
(PCB, no soldering & silk screen)
Next, it is a very thin copper foil layer, and it is pressed against the substrate through heat and the binder in the production. On the double panel, the copper foil is pressed against both the substrate. At some low-cost occasions, copper foil may only be pressed on one side of the substrate. When we mention the "double panel" or "two-layer board", we refer to our two-layer copper foil. Of course, in different PCB designs, the number of copper foil layers may be so few, or more than 16 layers.
The thickness species of the copper layer is more, and the unit is used in units, generally use copper uniformly covered a square foot weight (oz). Most of the PCB has a copper thickness of 1oz, but there are some high-power PCBs that may use 2Oz or 3oz copper thickness. The ounce (OZ) is converted per square foot, probably 35 um or 1.4mil copper thickness.
Soldermask
It is a solder resist layer on the copper layer. This layer makes the PCB look green (or sparkfun's red). The solder resist layer covers the traces of the copper layer to prevent traces and other metals, solder or other conductive objects on the PCB. The presence of the solder resist layer allows you to be welded in the correct place and prevent the solder from picking up the bridge.
In this example, we can see that the solder welding covers most of the PCB (including traces), but exposes silver holes and SMD pads to facilitate welding.
In general, the soldering welding is green, but almost all colors can be used to prevent welding. Sparkfun's card is mostly red, but the IOIO board has been used in white, and the lilypad board is purple.
Silkscreen (silk screen)
On the solder resist layer, it is a white silk screen. Microfits, numbers, and symbols are printed on the silk printing of the PCB, which can be easily assembled and guided to better understand the design of the board. We often use the symbol of the silk print layer to indicate some of the feet or LED functions.
The silk print layer is the most common color is white, and like, the silk print layer can be made almost any color. Black, gray, red or even yellow silk screens is very much. However, there are very few a variety of silk print layers on a single board.
Terminology (Terminology)
Now you know the structure of the PCB, let's take a look at the PCB-related terms.
The copper ring on the metallized hole on the PCB.
Examples of Annular Rings.
DRC - Design rules check. An inspection design contains a wrong program, for example, the trace is short, the trace is too thin, or the drilling is too small.
Drilling hits - the deviation used to represent the drilling position and the actual drilling position required in the design. The incorrect drilling center caused by the blunt drill bit is a general problem in the manufacturing of PCB.
Not too accurate Drill Hit diagram
(Golden) Fingers - Bare metal pads on the edge of the board, generally used to connect two boards. For example, the edge of the expansion module of the computer, memory bar, and old game card.
Stamp hole - except for V-CUT, another alternative scrap design method. Use some continuous holes to form a weak connection point, you can easily divide the board from the scrap. Sparkfun's ProtosNAP board is a better example.
The stamp well on Protosnap makes the PCB simple bend.
Welding - a portion of the metal in the surface of the PCB, used to welder the device.
The left is a plug-in pad, the right side is a patch pad
Puzzle - a large circuit board composed of many separate small boards. Automated circuit board production equipment often issues problems when producing small boards, combining several small boards together, can speed up the production speed.
Steel net - a thin metal template (or plastic), placed in the PCB, allows the solder through certain parts of the PCB.
Steel net (original map, find the map)
Pick-and-place - put the components on the machine or process on the wiring board.
Plane - a continuous copper skin on the circuit board. Generally, the boundary is defined instead of the path. Also known as "copper"
The picture shows that there is no trace on the PCB, but there are copper
Metalized via - a hole on the PCB, comprising a hole ring and an electroplating hole wall. The metallized via may be a plug-in connection point, a layer of signal, or a mounting hole.
A plug-in resistor on the FABFM PCB. The two legs of the resistor have passed through the via of the PCB. Electroplating hole walls can connect the traces of the PCB to both sides together.
POGO PIN - Temporary contact points of spring support, generally used as test or burning procedures.
There is a pointed Pogo pin, which is used in the test needle bed.
Reflow soldering - melts solder to connect the pads (SMD) and device pins together.
Silk print - letters, numbers, symbols, or graphics on the PCB board. There is only one color on the basically on each board, and the resolution is relatively low.
The silk screen pointed out that this LED is a power indicator.
Sloth - refers to what is not a circular hole on the PCB. The slot can also be plated with electroplating. Since the slot requires additional cutting time, the cost of the board is added.
Complex slots on the Protosnap - Pro Mini board. There are also many stamp holes. Note: Since the grooved tool is circular, the edges of the slot cannot be completely angled.
The solder paste layer-The solder paste layer formed by the steel net is formed on the pad of the surface of the surface of the surface of the surface of the sheet. During the reflow process, solder paste melts, establish reliable electrical and mechanical connections between pads and device tubes.
Before placing the element, a short solder paste layer on the PCB, remember to understand the definition of the steel network.
Solder furnace - furnace of welding insert. In general, there is a small amount of melted solder, and the board can be passed rapidly, and the exposed pin is welded.
Bardeze - To prevent short circuit, corrosion, and other problems, the top of the copper will cover a protective film. The protective film is generally green, or other colors (sparkfun red, Arduino blue, or apple black). Generally referred to as "soldering".
Solder Mask Covers Up The Signal Tracs But Leaves The Pads To Solder To. Solder covers the signal line, but the pad is exposed to facilitate welding.
The two connected pins on the tin-device are connected together by a small drip solder.
Surface mount - a suitable method of assembly, the device only needs to be placed on the board, does not need to pass the device pin through the via on the board.
Thermal welding - refers to a short walk between the connection pads to the plane. If the pad does not do proper heat dissipation design, it is difficult to heat the pad to sufficient welding temperature when welding. Inappropriate heat dissipation pad design, it will feel that the pads are more viscous and the return weld is relatively long. (Translator's note, generally hot pads do in the plugin and wave welding contact. I don't know why reflow, reflow mainly considers thermal balance, and prevents the monument.)
On the left, the pad is connected to the ground plane by two short traces (hot pads). On the right, the via is directly connected to the ground plane, and there is no hot pad.
Track - on board, generally continuous copper path.
A connection reset point and the fine lines of other places on the board. A relatively thick line is connected to a 5V power point.
V-score - An incomplete cut of board cards can be broken by this line. (Translator Note: China is often called "V-CUT")
Facing - a hole on the board, generally used to switch the signal from one layer to another layer. The plug hole refers to covering the solder soldering on the via to prevent welding. The connector or device pin is apertured because it is necessary to weld, generally not a plug hole.
The positive opposite of the same PCB is positive. This via hole transmits the signal through the borehole on the board, is transmitted to the back.
Welding - a method of welding insert device. The plate card is homogenous through a melt solder furnace that produces stabilized peaks, and the soldering of the solder foot and the exposed pad are welded together.
Brief introduction how to design your own PCB card
Designing Your Own! Design yourself!
Do you want to start designing your own PCB. The curved curves in the PCB design are too complicated here. However, if you really want to start, there are several points below.
Find a CAD tool: there are a lot of low price or free options in the PCB design. When you find a tool, you can consider the following points.
Forum support: Is there many people to use this tool? More people use it, easier you to find the already designed package of devices you need.
It is easy to use. If you are not easy to use, you will not use it.
Performance: Many programs are restricted to design, such as layers, number of devices, and board size. Most need you to buy authorization to upgrade performance.
Suppressibility: Some free procedures do not allow export or migration to other software, limit you in the unique vendor. Possible software's low price and convenience are worthy of such pay, but sometimes it is not worth it.
Go see the layout design of others. Open source hardware makes this more easily.
Exercise, practice, or practice.
Maintain low expected value. The first board you designed may have a lot of problems, but the 20th may have a lot, but there will be some problems. But it is difficult for you to clear all questions.
The schematic is quite important. Try to design a PCB board that has no good schematic support is futile. "
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