This is continuing of part one. The following advice is for how to solder SMD parts with improved technology.
Soldering Oven isolation
As an isolation material, their glass insulation can be used. In this case, glass insulation was packed in aluminum foil:
Inspected improvement in heating speed:
- 0.95% without isolation;
- 1.50% with isolation only inside oven;
- 1.72% full isolation.
Preparing the mask for applying solder paste
Using the mask for applying solder paster may improve solder quality, and the board may look more professional.
As mask material is a plastic plate of 0.2mm used. Mask also can be etched as a usual circuit board.
If circuit design is made using Eagle CAD software, then make a mask go to Tools->DRC->Masks. In the field, CREAM chooses minimum 0, maximum10mil. In the field %, values can be corrected.
In order to expose negative of SMD plates in Eagle select layer tCream:
- File->CAM Processor;
- Select layer Dimensions and tcream;
- Select in Devices option PS_INVERTED;
- make sure that Scale is equal to 1;
- File: name.ps
- Process Job;
- File name.ps should be placed in the working directory of the project;
- Set GSView or another environment for reading .ps files;
- Open the name.ps file and print it.
It is most convenient to etch the mask plate as a usual circuit board. For this special brass plate may be used, which has both sides covered with a photo-resistive coating. Peal one protective film another leave as it is. This way, you can etch through-hole, not all plates.
Next stage is putting cream on
First of all, fix the mask to the board so that mask area matches SMD solder areas:
apply cream smoothly by using a strip:
Hold the strip at the angle of 45 degrees so the paste distributes evenly:
Take the mask off the circuit board. Try to remove it vertically so that the solder nicely stays on the board.
Then put SMD components on the mask by slightly pressing them down. Make sure SMD parts are well centered.
Put the board into the oven, as discussed earlier. And it would help if you got a nice circuit board:
Soldered SMD board looks more beautiful and smooth
Few problems may occur while soldering with soldering paste in the oven—one of the short circuit between SMD legs. Don’t panic. Just apply enough flux and use solder remover. Next time make mask holes smaller when designing Eagle.
Sometimes solder paste may dry out without soldering parts. This means that oven heats too slowly. One os solutions may be to shorten drying time.