High Pin Count QFP Alignment Tool

I tried this guide. But over 36 pins on a side, proper alignment is an issue 

1.  initial alignment was difficult
2. correct placement on all four edges (36 pins x 4)
3.  holding the correct alignment difficult  

I came up with a process to create a 3D-printed alignment tool

In Kicad 

1. Add 2 or more alignment holes near the chip. 
2. Find a proper 3D model for IC 
3. Verify Kicad 3D model in the viewer 
4. Scale chip 3D model 1.03% (or more) so that the fit of the IC is not too tight
5. Export Kicad 3d model of board & chip model 

 

Modify Kicad export 

Fill in areas under the pin for the next step.  I used Tinkercad. 

Create a model of a hold-down block 

1.  Import the 3D Kicad model with extra fill 
2.  Create a rectangle that will partially cover QFP  model and alignment holes. 
3.  Position so that the rectangle goes to the bottom of the chip package (usually a small space is between the board on the package). May need to add alignment pins that go through the board's alignment holes. 
   
   
   
4.  Subtract the 3d Kicad model from the block of step #2. 

 

3D print alignment block 

1. Very fine layers like 0.1mm, 30% fill. 
2. Print 
3. Clean up the alignment pins and test fit to the PCB
4. Check with QFP part

Usage.

1. Press the QFP part into the alignment block. I will be tight, but should not warp the pins

2. Best if the pin 1 location is visible.

3. There are two ways that QFP can be positioned in the block, but only one way will align with the footprint properly.

4. Solder down the exposed pins while holding down QFP before removing the alignment block.