soldering points

Circuit board welding is a discipline, recently Shenzhen Qinji electronic small brother learning to weld, in the welding process summarized some of the welding methods, welding to pay attention to the problems and skills, I hope to help you.

1. Points desoldering method

PCB on the resistance, capacitance, common inductance, connecting wires, etc., only two soldering points, can be used to remove one end of the soldering point of the lead, and then remove the other end of the soldering point of the lead and will be components (or wire) out.

2. Centralized desoldering method

Integrated circuits, medium-frequency transformers, multi-lead connectors and other welding points are many and dense, switch, transistor and vertical device components such as welding points are very close to each other. The above components can be used to centralized desoldering method, the first soldering iron and tin tools, one by one will be soldered on the soldering point suction, and then use the tin tube will be separated from the component leads and pads one by one, and finally pulled off the components.

3. Intermittent heating desoldering method

For plastic skeleton components, such as intermediate frequency transformers, coils, line output transformer, etc., their skeleton is not high temperature resistance, and the lead is more dense, it is appropriate to use intermittent heating desoldering method. Desoldering, first heated with a soldering iron, suction welding point solder, revealing components lead profile, and then tweezers or poke the needle to pick open the pad and the lead between the residual solder, and finally with the tip of the soldering iron on the lead is not picked open individual welding point heating, to be melted solder, while hot, pull off the components.

1. After getting the bare PCB board should first carry out an appearance check to see if there are short circuits, circuit breakers and other issues, and then familiarize themselves with the development of the board schematic diagrams, schematic diagrams and PCB silkscreen layer for comparison, to avoid the schematic diagram does not match the PCB.

2. PCB welding materials required to prepare complete, should be classified components, according to the size of all components into several categories, to facilitate subsequent welding. Need to print a complete material schedule. In the welding process, did not finish welding a, then use a pen to cross out the corresponding options, so as to facilitate subsequent welding operations.

Welding should be taken before wearing static electricity ring and other anti-static measures to avoid static electricity on the components caused by damage. Welding equipment required to ensure that the soldering iron tip is clean and tidy. Recommended for the first time to choose a flat corner of the soldering iron, such as 0603 type package components such as soldering iron can better contact the pad, easy to weld.2 oz copper thickness in mm Of course, for experts, this is not a problem. 3.

3. Select components for welding, should be in accordance with the components from low to high, from small to large order for welding. So as not to weld the larger components to the smaller components of the welding inconvenience. Priority welding integrated circuit chips.

4. Before welding the integrated circuit chip to ensure that the chip is placed in the correct direction. For the chip silk screen layer, the general rectangular pad indicates the beginning of the pin. Welding should be fixed first chip a pin, the position of the components to fine-tune the chip after fixing the diagonal pins, so that the components are accurately connected to the position after welding.

5. SMD ceramic capacitors, voltage regulator diodes in the voltage regulator circuit without positive and negative points, light-emitting diodes, tantalum capacitors and electrolytic capacitors need to distinguish between positive and negative. For capacitors and diode components, generally have a significant identification of the end should be negative. In the SMD LED package, along the direction of the light for the positive - negative direction. For silkscreen marking for the diode circuit diagram package components, there is a vertical line at one end should be placed on the negative end of the diode. 6.

6. For the crystal, passive crystal oscillator generally only two pins, and no positive and negative points. Active crystal oscillator generally have four pins, need to pay attention to the definition of each pin to avoid welding errors. 7.

7. For plug-in components welding, such as power module-related components, the device pin can be modified before welding. After the components are placed and fixed, generally on the back through the soldering iron will melt the solder by the pad into the front.plated through hole vs via Solder does not have to put too much, but first should make the components stable. 8.

8. Welding process should be recorded in a timely manner found in the PCB design issues, such as installation interference, incorrect design of pad size, component packaging errors, etc., for subsequent improvement.

9. After welding should use a magnifying glass to view the solder joints, check whether there is a false soldering and short-circuit and so on.

10. circuit board welding work is completed, should use alcohol and other cleaning agents to clean the surface of the circuit board to prevent the circuit board surface attached to the iron filings make the circuit short-circuit, but also to make the circuit board more clean and beautiful.

Electronic circuit board welding skills

Many beginners welding electronic circuit boards are very unstable, easy to short circuit or broken circuit. In addition to the layout is not reasonable and poor soldering and other factors, the lack of skills is one of the major causes of these problems. Mastering some skills can make the circuit reflected in the physical hardware to greatly reduce the complexity, reduce the number of flying wires, so that the circuit is more stable.

1. Preliminary determination of the power supply, ground layout

Power supply throughout the circuit, a reasonable power supply layout to simplify the circuit plays a very critical role. Some circuit boards are arranged with copper foil throughout the board, which should be used as the power and ground lines; if there is no such copper foil, you also need to have a preliminary planning for the layout of the power and ground lines.

2. Good use of component pins

Circuit board soldering requires a large number of cross-connections, jumper wires, etc., do not rush to cut the excess pins of components, sometimes directly across to the surrounding components to be connected to the pins will be twice as effective. In addition, in line with the purpose of saving materials, you can cut the component pins collected as jumper materials.

3. Setting jumpers

Especially want to emphasize this point, set more jumpers can not only simplify the connection, but also much more beautiful.