# Audio Tone Control

Thore Lencer, Prof. Dr.-Ing. Ralf Sommer

# GaSt Praxisseminar WS 25/26

[![IMG_20250916_132138.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250916-132138.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250916-132138.jpg)

Probably our most complex double sided PCB so far.

Size ~60x50mm

[![IMG_20250916_132154.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250916-132154.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250916-132154.jpg)

We are working on soldering this board with our Reflow-oven.

We want to try making the solder-paste stencil with our vinyl-cutter:

[![](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/image-1758200650767.png)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/image-1758200650767.png)

Above is a screenshot from GoSign, our software for the Summa S3 T75.

[![](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/image-1758200692402.png)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/image-1758200692402.png)

This is an attempt with a speed of 10mm/s instead of 800mm/s:

<video controls="controls" height="472" id="bkmrk--5" src="https://unikat-ilmenau.de/wiki/attachments/125?open=true" width="839"></video>

The first stencil looks very promising!

[![4032-3024-max.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/Tjn4032-3024-max.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/Tjn4032-3024-max.jpg)

[![IMG_20250925_151927.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250925-151927.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/img-20250925-151927.jpg)

<video controls="controls" height="473" src="https://unikat-ilmenau.de/wiki/attachments/126?open=true" style="width: 841px; height: 473px;" width="841"></video>

[![IMG_20250925_152335.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250925-152335.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/img-20250925-152335.jpg)

[![IMG_20250925_154737.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250925-154737.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/img-20250925-154737.jpg)

[![IMG_20250925_155428.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250925-155428.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/img-20250925-155428.jpg)

[![IMG_20250925_155526.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/scaled-1680-/img-20250925-155526.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-09/img-20250925-155526.jpg)

### Reflow soldering

Placing all components:

[![IMG_20251001_142141.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-10/scaled-1680-/xOuimg-20251001-142141.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-10/scaled-1680-/xOuimg-20251001-142141.jpg)

[![IMG_20251001_153336.jpg](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-10/scaled-1680-/img-20251001-153336.jpg)](https://unikat-ilmenau.de/wiki/uploads/images/gallery/2025-10/scaled-1680-/img-20251001-153336.jpg)

<video controls="" height="473" src="https://unikat-ilmenau.de/wiki/attachments/127?open=true" width="841"></video>

Good settings for perfect TSSOP package and 0,4mm traces copper milling: 0.2mm v bit but insert 0.25mm in modsproject with 0.25 stepover and 4 offsets

Solder mask removal: Solder mask removal bit; Z calibration with multimeter; then step up by 0,12mm and step down slowly if needed; cure UV mask for 5min first, then mill, then final-cure; cut speed 5mm/s; plunge speed 2mm/s, spindle 6000rpm

Drill after solder mask application! Elsewise solder mask gets into the holes and copper can be destroyed when there are thin pad rings