Looking for a more flexible solution for your PCB needs? Check out our Soft Board SMT options! #FlexiblePCB #SoftBoard #SMT #ElectronicDesigns. Learn more on our website now!
Introduction
Looking for a more flexible solution for your PCB needs? Check out our Soft Board SMT options! #FlexiblePCB #SoftBoard #SMT #ElectronicDesigns. Learn more on our website now!
Flexible circuit board refers to a foldable printed wire circuit board formed on copper foil with PET(Polyethylene terephthalate) or PI(Polyimide) as the substrate, which can properly carry a wide range of active and passive components and accessories. Through proper assembly design, it is widely used to connect with each module of electronic products.Short for soft board or FPC.
Key Advantages
Flexible circuits provide an incredible amount of design versatility because they are lightweight, bendable, foldable, and can be configured to match a range of size and space requirements. The four key advantages of using flexible circuits for electronics include:
1.Reduced size & weight. Compared to standard printed circuit boards (≈0.063” thick), flex circuits provide a dramatic decrease in package size and weight. Flex circuits, typically just 0.004”-0.010” thick, are even thinner and lighter than traditional cable options.
2.Solution to interconnect challenges. Interconnect problems can often be solved by flex circuits, which integrate the interconnects into the part. Thus, flexible circuits eliminate the need for expensive cables and connectors.
3.Reduction in assembly costs. With the interconnections built into the flex circuit, fewer connectors are required, and thus less soldering. The ability to pre-form the flex circuit assembly, along with its inherent flexibility, allows quicker installation, particularly in hard-to-reach areas.
4.High performance & flexibility. Certain applications simply require circuits that can flex. Compared to other flexible options, flex circuits provide superior electrical and mechanical performance.
Disadvantages
It has high cost, long cycle and high reliability test method. Printed circuit is the product of electronic technology, multi-function, high speed, small volume and large capacity. With the development of electronic technology, especially the wide application of large scale and very large scale integrated circuits, fine lines appear in the direction of fast, high precision and high number changes with high density of multilayer printed circuit.
Application
1.Mobile phones, which emphasize the weight and thickness of flexible circuit boards. It can effectively save product volume, easily connect the battery, microphone, and button into one.
2.Computer and LCD screen, which uses a combination of flexible circuit board configuration and thickness, by converting digital signals into pictures, through the LCD screen
3.CD walkman, which focuses on the three-dimensional assembly characteristics of the flexible circuit board and the thickness.
4.Diskette: whether hard disk or floppy disk, all rely on the high softness of FPC and the ultra-thin thickness of 0.1mm to complete the fast data reading, whether it is PC or NOTEBOOK.
Welding method
1.before welding on the welding pad coated with flux, with a soldering iron treatment, so as to avoid poor soldering pad or oxidation, resulting in bad welding, chip generally do not need to be treated.
2. Carefully place the chip on the PCB board with tweezers and be careful not to damage the pins. Align it with the pad and make sure the chip is positioned in the correct direction. Set the temperature of the soldering iron to more than 300 degrees Celsius, dip the tip of the soldering iron with a small amount of solder, press down on the aligned position of the chip with the tool, add a small amount of flux on the two diagonal position of the pin, still press down on the chip, welding the two diagonal position of the pin, so that the chip is fixed and cannot move. Recheck the alignment of the chip after welding the corners. If necessary, adjust or remove and realign the PCB.
Soldering Tips for Welding SMT Components on Circuit Boards
3. When starting to weld all the pins, solder should be added to the tip of the soldering iron, and all the pins should be coated with flux to keep the pins wet.Touch the end of each pin of the chip with the tip of the soldering iron until solder is seen flowing into the pin.When welding, keep the tip of the soldering iron parallel to the welded pin to prevent overlap due to excessive soldering.
4. After welding all the pins, soak all the pins with flux to clean the solder. Suck up excess solder where needed to eliminate any short circuits and lap joints.Finally, inspect for virtual welding using tweezers. After completing the inspection, remove the flux from the circuit board and carefully wipe it with a stiff brush soaked in alcohol in the direction of the pin until the flux disappears.
5.For welding SMT resistance elements, first apply solder to a spot on the tin, and then place the element on the end. Next, use tweezers to clamp the element and weld it on the end. Finally, check whether it is properly positioned. If it is, weld the other end.
Reasons for poor FPC welding
1.Too much solder, forming solder tin accumulation; Too little solder to cover the spot.
2.Cold welding. The soldering iron does not melt the solder completely when the temperature is too low or the heating time is insufficient, causing infiltration and the surface of the solder is not bright, and small cracks appear.
Inclusion of a layer of rosin between the solder, components or printed circuit board causes poor electrical connection. If the rosin is not heated enough, the solder joint will have a layer of tan rosin film. If the heating temperature is too high, a carbonized rosin black film will appear under the solder joint. For an underheated rosin film, you can use a soldering iron to repair the welding. To address the formation of a black film, it is necessary to remove the excess net solder, clean the surface of the welded components or printed circuit board, and then re-weld them.
4.solder bridge. Refers to the excessive amount of solder, resulting in short circuit between the solder joints of components. This is especially important when welding ultra-small components and tiny printed circuit boards.
5.Excessive flux, a lot of rosin residue around the solder joint. When a small amount of rosin remains, you can use a soldering iron to gently heat again to allow the rosin to evaporate, or you can dip in a cotton ball with no water alcohol, wipe off excess rosin or flux.
6.The solder on the surface of the solder to form a sharp point. This is mostly due to insufficient heating temperature or too little flux, as well as the soldering iron left the solder joint Angle caused by the wrong.
Repair
There are two main rework methods, one is tin drag welding, the other is pull welding.
Pulling and soldering method: The tip of the soldering iron should be perpendicular to the golden finger. The soldering iron is about 30 degrees from the inside of the golden finger and the PCB board, and pulled outward with an appropriate force.
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