+++
title = 'Verbesserung des UV-Belichters'
date = 2026-04-10T18:09:20+02:00
draft = false
toc = true
cover = 'cover.png'
+++


## Introduction {id=introduction}

After a long period of using the [unit]({{< ref "posts/2025/04/diy-uv-pcb-exposure-unit.md" >}}) with exposure times exceeding 40 minutes in PCB manufacturing, it was finally time for the previously announced upgrade. The goal was to double the number of LEDs from 48 to 96. This is intended to achieve more uniform coverage of the exposure area, as well as, of course, shorter exposure times.


## 1. PCB Problems {id=problems}

The increased number of LEDs also increases the power requirement. And that posed a problem - the first control board was only rated for 1A at 12V. So a new one is needed - the exposure unit exposes its own new controller board.

![The layout](pcb_arrangement.png)

Compared to the first version, the advantage of PCBs over breadboards is clear:

{{< figure src="pcb_comparison_old_new.jpg" alt="The new and old controller boards compared; the new one is significantly smaller than the old one" caption="Left: new - right: old" >}}

A double-sided layout made it possible to significantly reduce the amount of space required.


## 2. Fresh coat

To further improve efficiency through reflection, the new circuit board is also sprayed with chrome-effect paint, just like the old one. However, because the smaller distance between the LEDs also requires a different placement of the two LED carrier boards (slightly less distance in the middle to maintain uniformity), the interior of the exposure unit had to be repainted for aesthetic reasons - otherwise, the footprints of the old boards would still be visible.

![Before-and-after image of the coating on the carrier circuit boards and the interior of the exposure unit](before-after-spray.png)


## Result

The result is impressive - you can now barely see any individual light cones at the exposure distance (where the circuit board is placed), resulting in a very uniform image.

{{< figure src="before-after_homogenity.jpg" alt="Before-and-after image of the illumination: Very uniform on the left, individual light cones still visible on the right" caption="Left: new (48x) LED board; right: old (24x) LED board" >}}

In the image, a piece of paper was placed on the glass pane to determine the illumination of the surface. The old circuit board (24 LEDs) was installed on the right, and a new one (48 LEDs) on the left.
The new exposure times could not be determined precisely due to time constraints, but they will be in the range of 15-20 minutes.