How has the patched PCB board been wave soldered?
Today, labor costs are rising, the factories are afraid of getting the order with DIP components. However, electronic products often need to be soldered with some DIP components, which make the factories very headache.
Now, I would like to introduce a method to improve the backhand welding efficiency of the DIP material, hoping to solve the problem of your headache.
In fact, the red glue process can improve the efficiency of backhand welding, let us first look at how does the red glue work.
As the name suggests, the red glue process uses red glue for the patch. When making a stencil, not open the position of the component PAD, but rather a slot in the middle of the component. Brushing the red glue on the stencil, then pass to the SMT machine, so the components are glued to the PCB board. After inserting the DIP components, pass to wave soldering, the soldering pad of the component will be soldered in the tin furnace. Then the pads of the component are soldered completely.
Figure 1 Red glue process
There are some problems in the red glue process: as can be seen from Figure 1, the red glue will have a certain thickness, and the hardening process will raise the components, which makes a gap between the component pad and PCB board PAD. Finally, it leads to poor soldering and Pseudo Soldering.
In addition, the red glue will become very hard after passing the wave soldering. it will be very troublesome, if you need to repair the components.
What is more, when the red glue is too hot in the wave soldering, the components are easy to drop, especially for IC.
The method introduced today can avoid these problems in the red glue process. Let's look at a few pictures first.
Figure 2 A fixture
The fixture of Figure 2 has some holes and slots on it:
The holes are required for backhand welding, and the pins of the DIP components can be passed from the holes. When the fixture is placed on the solder machine, only those holes can be touch with solder;
The slots are for the SMT component, big components with big slots, small components with small slots. In this way, the patch-completed PCB board can be placed perfectly on the fixture.
Figure 3 PCB board for the fixture
In Figure 3, each PCB board has two larger-sized chips, one close to a square and one rectangle. With these two chips and the slots in Figure 2, it is known that the how to put the PCB board on the fixture.
Figure 4 The fixture is placed on the bottom side of the patched PCB
Figure 4 shows how the board with the patch components is placed on the fixture. Is it clear?
Figure 5. The fixture is placed on the backside of the patched PCB
Let's take a look at the back side. I don't need to explain that everyone knows that it is very easy to plug in. This method can significantly improve the post-welding efficiency, but there can be no other patch material near the pad of the DIP components. If it is too close, the pad cannot be exposed, and it needs to be manually repaired.>