PIP (Pin in Paste) technology for soldering trough hole components
PIP is a technology for assembling through hole components using a conventional reflow soldering process. The process is also known as THTR (Trough Hole Technology Reflow).
Most PCB”s that contain SMD components usually also contain some through hole components, such as connectors, switches, capacitors and so on . The principle of PIP is that through hole components are placed into PTH holes with SMT solder past and then reflow soldered with the other SMT components together.
We judge this can be a technology of interest for electronics developers that decide to assemble their prototypes themselves.
The next figure shows the process sequence we advise :
Important parameters for this process are hole and pin sizes, boards thickness, thickness and opening of the stencil , used paste printing technique and used paste.
It is obvious that only components that can withstand the reflow soldering temperatures can be soldered this way.
Most datasheets for PIP connectors also contain useful infomation such as the recommended stencil design.
Some hints based on our experience to give you the best results:
- Reduce the hole size as small as possible for the component pin to be soldered
- Avoid big annular rings
- Do not put via holes in areas where solderpaste needs to be printed
- Position the squeegee at an angle of 45° to the stencil to improve the pressure of the paste
- Increase the size of stencil apertures to overlap on the area around the pth hole (overprint) – when the solder paste melts, it will flow into the holes.
Image of the bare bottom side of the pcb after printing the solderpaste on the top side :
Cross-section of the component pin after soldering with PIP technology :
Advantages of the PIP technology
- You can spare one step in the assembly process, this reduces cost as well as time.
- All components are processed within one SMT solder process.
- Good wetting and less risk for solder bridges
- Connectors suitable for PIP generally require less board space, and are easier to repair then SMT connectors.
The Pin in Paste technology is very useful, because you can save time and manpower. We think this technology makes it easier for electronics developers to assemble prototypes in-house in a reliable, quick and affordable way.
More information about the equipment used in the test is available in our section on SMD reflow equipment