Dot matrix board (universal circuit board/hole board) is a kind of printed circuit board (PCB) which is covered with pads according to the standard IC pitch (2.54mm) and can be inserted with components and connections according to one’s own wishes, commonly known as “hole board”. Compared with professional PCB plate making, hole plate has the following advantages: low threshold, low cost, convenient use and flexible expansion. For example, in students’ electronic design competition, the works usually need to be finished in a few days, so most of them use hole boards.
Preparation before welding Before welding lattice board, you need to prepare enough thin wires for routing. Thin conductor can be divided into single strand and multi-strand (right of the above picture): single-strand hard conductor can be bent into a fixed shape, and can be used as jumper after peeling; Multi-strand thin wires are soft and messy after welding. The lattice board has the characteristics of tight pads, which requires our welding head to have high precision. It is recommended to use a pointed soldering iron with a power of about 30 watts. Similarly, the solder wire should not be too thick, so it is recommended to choose one with a wire diameter of 0.5 ~ 1 mm.
The basic steps of manual welding operation: mastering the temperature and welding time of the soldering iron, and selecting the appropriate contact position between the welding head and the solder joint can get a good solder joint. The correct manual welding process can be divided into five steps:
(1) Step 1: Prepare welding (Figure (a))
Take the welding wire with the left hand and the soldering iron with the right hand, and enter the welding standby state. Welding head shall be kept clean, free of oxides such as welding slag, and coated with a layer of solder.
(2) Step 2: Heat the weldment (Figure (b))
Welding head leans against the joint of two weldments and heats the whole weldment for about 1 ~ 2 seconds. For soldering components on printed circuit boards, attention should be paid to making welding head contact with two welded objects at the same time. For example, in Figure (B), the wires and terminals, the leads and pads of components should be heated uniformly at the same time.
(3) Step 3: Feed welding wire (Figure (c))
When the welding surface of the weldment is heated to a certain temperature, solder wire contacts the weldment from the opposite side of the soldering iron. Note: Don’t send solder wire to welding head!
(4) Step 4: Remove the welding wire (Figure (d))
When the welding wire melts a certain amount, immediately remove the welding wire to the upper left 45 direction.
5] Step 5: Remove the soldering iron (Figure (e))
After the solder pad and the welding part of the weldment are soaked with solder, move the soldering iron 45 to the right and end the welding. From the beginning of the third step to the end of the fifth step, the time is about 1 ~ 2 seconds.
Points for attention in welding:
(1) Keep welding head clean.
Increase the contact area to speed up heat transfer.
(3) Heating depends on solder bridge.
(4) soldering iron evacuation is exquisite.
The evacuation of soldering iron should be timely, and the angle and direction of evacuation are related to the formation of solder joints. Figure 5.18 shows the influence of different evacuation directions of soldering iron on the amount of tin in solder joints.
5] Do not move until the solder solidifies.
[6] The amount of solder should be moderate.
Once flux dosage should be moderate.
Being don’t use welding head as a tool to transport solder.
Ideal appearance of solder joints:
(1) The shape is approximately conical and the surface is slightly concave, showing a diffuse slope shape, centering on the welding wire, and symmetrically spreading in a skirt shape. The surfaces of virtual solder joints tend to protrude outward, which can be identified.
② On the solder joint, the connection surface of solder is concave and naturally transits, the junction between solder and weldment is smooth, and the contact angle is as small as possible.
③ Smooth surface with metallic luster.
④ No crack, pinhole and slag inclusion.
Welding method of dot matrix board: For the layout of components on the hole board, most people are used to “follow the vine and touch the melon”, that is, the key components such as chips are the center, and other components meet each other’s needs. This method is planning while welding, which reflects order in disorder and has high efficiency. However, this method is not suitable for beginners because of their inexperience. Beginners can first make a preliminary layout on paper, then draw it on the front (component surface) of the hole plate with a pencil, and then plan out the routing for their own welding. For the welding method of lattice plate, the thin wires mentioned above are generally used for flying wire connection. Flying wire connection is not too skillful, but try to make the horizontal and vertical wiring as neat and clear as possible. At present, there is a popular method on the Internet, which is called the method of connecting wires with tin. The technology is good and the performance is stable, but it wastes tin. Pure tin wiring is difficult, and it is influenced by tin wire, personal welding process and so on. If a thin copper wire is pulled first, and then the welding is carried out with the thin copper wire, it is much simpler. The welding method of hole plate is very flexible, and it varies from person to person. Just find the method that suits you.
