Flex PCBA soldering method

First, artificial soldering iron welding (manual soldering)
Manual soldering flexible board in the circuit board is the most inexpensive process of all flexible board soldering processes, some even do not need to use the jig can work, but the quality of its soldering is also one of the most unreliable processes because manual soldering is easy to cause empty soldering, false soldering, false soldering, short-circuit bridging and other quality problems. This is because the manual soldering soft board is easy to move away from the iron head and the solder is not yet cured when moving or warping, until the solder is cured after the formation of false soldering, such as the results of empty soldering. Therefore, it is best to use a heavyweight in the manual welding on the soft board until the welding is completed and removed, which can greatly enhance the welding yield. In addition, the soft board soldering gold finger is best to open a through-hole (PTH), you can increase the visual to confirm whether the soldering is good, but also to reduce the risk of short-circuit overflow tin. flex pcba

Generally speaking, if the design has not been finalized (Lock-down), to reduce the cost of fixture design and production, you can use a small amount of manual soldering iron soldering soft board operations to the RD to do functional verification. It is strongly recommended not to solder manually when mass production.

Second, HotBar (Haba) soldering
HotBar (Haba) welding principle is the use of the so-called [pulse current (pulse)] flow through the molybdenum, titanium and other metal materials with high resistance characteristics produced by the [Joule heat] to heat the [hot pressure head (thermodes/heater-tip)], and then by the hot pressure head heating and melting the PCB has been printed on the solder paste and FPC connection to achieve the purpose of welding.

Therefore, HotBar operation must have a HotBar machine, but also have a carrier (carrier) to fix the FPC in the PCB, as long as the FPC and PCB design are good, basically can achieve mass production and a certain yield target.
HotBar FPCB near the limit of parts
HotBar FPCB Flexible Board Design Considerations-PTHs
HotBar HotPress FPCB and PCB solder pad relative position recommendations
HotBar FPCB soft board design-avoid stress concentration, line breakage
Then there is the pitch size of the FPC gold finger, the larger the pitch, the easier it is to produce, and the higher the yield, but the design requirements are getting smaller and smaller, which also causes HotBar more and more difficult to do, the yield straight down the dilemma.
The last is the process control issues. For example, the amount of solder paste control, HotBar when the flux is applied in place, HotBar temperature, pressure, time settings, and HotBar machine capacity (whether the pressure of the hot press head can be programmed).

In addition, some HotBar soft boards cannot be designed to achieve effective heat conduction, and it may be necessary to consider whether or not to use SnBi (tin-bismuth) low-temperature solder paste, but low-temperature solder paste is more brittle, so it is recommended to strengthen the auxiliary structure. flex pcba

PCBA board production
First of all, before the placement of the PCB light board baking process for dehumidification, and then put into production to complete the placement – insertion – testing – packaging, and shipping, the requirements of the production schedule within a week to complete the entire production process.
Reflow soldering, and wave soldering welding by its operating instructions to set the temperature curve. The preheating rate should not be too fast. Set the peak temperature at no more than 245 degrees Celsius, the higher the temperature, the greater the risk of exploding the board. For hand-soldered patch soldering, use a temperature-controlled soldering iron, set the temperature at 350 degrees Celsius, and control the soldering time at 2~3s to prevent localized overheating and the formation of potentially defective.

For CTI>600 PCBA production, the key to preventing the explosion of the board is to do a good job of prevention and quality control. To trace the production management of CTI>600’s PCBs. CTI>600’s PCB’s production management. They are the cornerstone of the prevention of burst boards.
In addition, in the PCBA assembly and production of thermal stress control, preventing the causative thermal stress factors of the burst board can completely reduce or even eliminate the impact of the burst board, can completely reduce or even eliminate the generation of the burst board. flex pcba

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