PCB herstellen

• Einführung in die Gestaltung von Leiterplatten mit KiCad
• KiCad Basics Tagebuch
• Assembly and Testing
• ZAM Badge 2024
• ZAM Badge - Cat with Knife

Einführung in die Gestaltung von Leiterplatten mit KiCad

 

Überblick

Teil 1. Ein Tag zum Erstellen eines Projekts mit KiCad - mit den Schaltplan- und PCB-Editoren sowie den Symbol- und Footprint-Editoren, um eine benutzerdefinierte Leiterplatte herzustellen.

Teil 2. Ein weitere Tag um die Platine zum Laufen zu bringen; Bestückung und Prüfung ist auch eingeplant.

Original Vorschlag (Englisch)

Teilnehmer

Vorkenntnisse 

Grundkenntnisse in Elektronik wären hilfreich aber nicht essentiell. 

Mitbringen

Material Kosten

Am 2. Tag entstehen Materialkosten. Der genaue Beitrag ist abhängig von der PCB Größe. Ein Betrag zwischen 10€ bis 15€ ist zu erwarten.

Anmeldung

smayze@yahoo.com 

Ort

ZAM Hauptstrasse, Erlangen.

Programm

Tag 1 - Sa. 4. Juni 2022

Basic project creation up to layout.

Time	Duration	Topic
10:00	30	COVID Testing. Introduction, house rules.
10:30	45	Introduction to KiCad + Circuit Creation
11:15	15	break
11:30	45	Library Management - Symbols and Footprints
12:15	60	Lunch
13:15	45	Layout
14:00	15	break
14:15	45	Wrap up and packup
15:00		finish

Tag 2  - Sa. 25. Juni 2022

Assembly, testing and troubleshooting.

Time	Duration	Topic
10:00	30	COVID Testing. Introduction, house rules.
10:30	45	Assembly
11:15	10	break
11:25	45	Assembly
12:10	60	Finish

 

Designdateien

Die Designdateien sind auf dem GitHub Repository ZAM_KiCad_Basics erhältlich.

 

KiCad Basics Tagebuch

Teil 2. Samstag 25.06.22

The boards were not completed during the first session. A deadline to complete the boards was set for the 13.06.22 to ensure that the boards would be back in time for part 2. The order was posted 11.06.22 and the boards arrived back 20.06.22 so in plenty of time for part 2.

We started the day with a commentary on the layouts and some of the things to watch out for. Steve then demonstrated his approach to soldering Surface Mounted Devices (SMD). The smallest part is 2mm x 1.27mm. Once the approach was demonstrated, they were left to assemble their boards. 

 

Once assembly was completed, then it was time to test the work. All the boards worked without any issues.

Things Learned and Improvements

The day went quite well. It was intended to be only a short session i.e. 2 hours and not as long as Part 1. Time-wise, it worked well and all were completed and packed up within 2½ hours. There is not much to consider to change in this case.

 

Teil 1. Samstag 04.06.22

Objective

The creation of projects in electronics requires the connection of various components to build a circuit. There are various means to achieve this - breadboard, verro-board. However there are many advantages to building an own Printed Circuit Board (PCB). The purpose of this workshop was to introduce the attendees to the KiCad electronic design tool so that they will gain the know-how and confidence to create their own PCBs. 

There were two goals for the event.

1. Introduce the attendees the work-steps required to create a PCB. This workflow is not unique to KiCad.
2. Have a set of design files ready to send for fabrication.

Method

A relatively simple (but not too simple - Falstad model) project was presented. The classic first project, a blinking LED project. The project was presented as our final goal that we needed to implement as a PCB.

There was quite a bit of information to get through. 

1. Creating a project.
2. Creating a schematic.
3. Creating and modifying the symbols for a schematic.
4. Assigning footprints to the symbols.
5. Creating and modifying the footprints.
6. Creating the layout.

Procedure

I opened the session with the question of why do we ant to create our own PCB? The answers that came back were consistent to what drew me into this area of electronic development.

• DIY home automation.
• Neatening up existing projects.
• Wanting to interface neatly with existing development boards.
• Create my own development board.

I showed my won example of neatening up a project. Where I presented a first attempt at creating my won door bell extension with what I knew at the time and using Verro board.

Old	New

 

We then started work. I introduced the software and the creation of the schematic diagram with an introduction to the symbol library and how you go about creating a new symbol or changing an existing one to suite the purpose of the diagram. It soon came apparent that a symbol does not need to exactly match the physical component that is going to be used in the circuit. The schematic is a design document to help the developer and other understand the operation of a circuit.

After lunch we moved onto the PCB Layout itself. Ideally the purpose of the class. I showed how to prepare the schematic for import into the PCB layout tool. The most important aspect being the footprints. A footprint is the physical form the component will take on the PCB. Each symbol must be associated to a footprint before the layout can be completed. The problem here is that for one symbol there could be any number of footprints to choose from. We need to consult the datasheet for the exact component we intend to purchase to ensure that out components will actually fit on our board and will be connect up correctly. This step should never be underestimated.

Another aspect of the layout I explained wat that we need to understand the design limitations and tolerances of the PCB fabrication house. Each house will have their own set of rules and we need to configure KiCad to help us adhere to those rules. This means we need to set up the minimum distances and widths allowed for the copper.

There is the question if this was a PCB creation workshop, how come we are preparing the design files to send off for fabrication? The answer is that the actual fabrication of the physical PCB is only one part of the process and actually not a significant part of the overall creative process of creating the design, assembling and troubleshooting. There is more than one technique for creating a PCB and ZAM does not yet have the facilities for either of these processes. Sending the boards off for fabrication is the simplest and most effective way to introduce the more important aspects of the creative process.

So at the end of the session, we now have some design files that can be sent off and on their return we will continue with the second part - the assembly and testing of the boards.

 

 

Things Learned and Improvements

This was the first KiCad workshop both for me and ZAM. In the planning it was important to me to make sure explain the design process workflow and highlight that at every stage of the process, we need to make design decisions. I consider this aspect is actually more important than the PCB software itself. However, I noticed there could have been a couple of tings done differently.

1. A Simpler project.
While the project itself seemed to be simple, and easy to explain, especially with Falstad Circuit, I tend to think now for a basic KiCad introduction, the concepts of symbol and footprint library management including symbol and footprint creation could be left off for a separate workshop.

2. Break the workshop up
While it was nice to have the full day to concentrate on the project, it was a long day and in the end the design files were not ready and had to be handed in a couple of days later. In thinking about point 1. above, with a simpler project, the workshop could be broken up into shorter, 2 hour, sessions that could be scheduled during an evening rather that taking up a whole day on the weekend. These session could then focus on specific aspects like the following list. The last three items are somewhat related but have differences that make them hard or too large to include in one session.

1. Schematic Creation
2. PCB Layout
3. Library Management
4. Managing a PCB project with GIT
5. Adding graphics to a PCB
6. Custom and Fun board shapes
7. Artistic PCB i.e. Creating Blinking Badges

 

 

 

Assembly and Testing

Assembly and Testing

Overview 

The assembly and testing of self-designed PCBs requires some extra equipment. Much of this has already been thought out on the Rapid Prototyping Elektronik page and in particular on the associated spreadsheet/list. I would like repeat some of the recommended items here. Another good reference for this is the Soldering Workshop presented by Binary Kitchen, Regensburg.

The kit for each attendee

• Lötstation
• Löt
• Schutzbrille
• Lötrauchabsaugung
• Metallschwamm
• Seitenschneider
• Pinzetten
• Drittehand
• Entlötpumpe und Entlötlitze
• ESD matte
• Lampe.

Advanced Gear

• Heißluftlötstation
• Reflow-ofen

Some of this equipment is already in ZAM. However, there is not enough to run any type of soldering workshop and the safety equipment is as yet not available - solder fumes extractor and safety glasses.

We could build our own Solder fume extractor. Binary kitchen have theirs as a kit. There are plenty of other examples on the Thingiverse. In my case, I created one from a PC cooling fan, an off-the-shelf case, a 12 V LED lamp and a flexible hose from a fire-lighter. I imagine we could come up with something in the middle.

 

 

 

ZAM Badge 2024

Überblick

Bei der Planung des VULCA-Treffens kam die Idee eines Badge als Konferenzpräsent und Lötübung auf. Die Idee besteht darin, die folgende Grafik zu nehmen und diese in eine Leiterplatte mit blinkenden LEDs hinter dem Auge und den Buchstaben umzuwandeln.

Projekt-Metadaten

ZAM-Badge-24 GitHub Repository

Jochen Hunger jochen.hunger@betreiberverein.de

Steve Mayze smayze@yahoo.com

Logbuch / Schritte

Tag 1 Zusammenarbeit

Ich habe schon früher Grafiken in PCBs umgewandelt. Ich wollte dieses Projekt unbedingt in Angriff nehmen, da ich einige Wochen zuvor an der KiCon Europe 2024 teilgenommen hatte und den Vortrag „Zusammenarbeit mit Künstlern, um schöne Platinen zu entwerfen“ sehr genossen hatte. Als Erstes musste ich mir das Konzept ausdenken. Auf Grundlage der Originalgrafik skizzierte ich eine mögliche Anordnung der PCB-Schichten.

Basierend auf dieser Skizze hat Jochen dann seine Vorstellungen dargelegt. Daraus ließe sich relativ einfach eine Leiterplatte entwickeln. Die Idee ist, Kopf und Buchstaben alle in der gleichen Farbe zu haben (die Lötmaske) und dann den Bereich hinter den Augen und um die Buchstaben herum frei zu lassen, damit die blinkenden LEDs hindurchscheinen.

Ich habe dies noch etwas weiter ausgeschmückt und mir Gedanken darüber gemacht, wo die Komponenten platziert werden könnten.

Tag 2. Erstellen des Designs

Once I had KiCad available I proceeded to turn the SVG of the graphic into a PCB. To achieve this, the layer feature of Inkscape was invaluable.

	The original image was exported as Front Copper (F.Cu). This will ensure that the section of the board that represents the head  and letters will be opaque and not letter any light through.
	The next layer to export as the solder mask. For the entire image was exported but this has to be converted to a negative since this defines where the solder mask should not go.
	This image is then taken into a graphics program such as GIMP or Krita and trimmed down as the entire outline for this design.
	The last layer is based on the entire image and converted to an outline. This is then expanded using the Outset tool. This will ensure that milling tool following the edge cut will not conflict with the actual image outline.

Once the layers are exported and verified, the layout of the board can begin. First of all, a simple circuit is created to defined the required parts. We don't have a lot of time for this project to try things out. So I opted to have space for three LEDs thought I believe only two will be required.

   

   

Tag 3. Montage und Prüfung

A week or so after uploading the design files to the fabricator, a panel arrived in the post. I had to assemble to see if there were any issues.

The assembly is quite simple. We start by soldering the LEDs first. The battery holder is large and the LED pads are quite close. There is a risk of damaging the battery holder if the soldering iron should touch it while soldering the LEDs.

The leads of the LEDs should be bent into place and cut to length. Make sure to take note of the anode and cathode of the LED. These leads need to connect to the appropriate pad. If they are connected the wrong way, you will not damage the LED. It just won't glow. The anode is the longer lead and should be placed on the pad marked with the plus (+) sign.

After the LEDs are soldered in place, then the battery holder and switch can be placed on the board. Like the LEDs take note of the orientation of the battery holder. Refer to the graphic below to see the correct orientation. The ⊕ marking on the battery holder should be bottom right as shown in the image.

The switch has no special orientation. The leads will need to be bent into shape so that they neatly touch their pads.

Note that for the battery holder and the switch you might need to apply more heat to get a good connection.

Bauteile

• 3mm LED - eye
• 5mm LED - ZAM letters
• CR2032 Knopfzellhalter
• Schalter

   

ZAM Badge - Cat with Knife

Überblick

Schumi thought it would be cool to have a badge available for Wintergalaktische Club-Mate Party 2025 (WCPM). The design would be based on a Cat with Knife pin.

[Photo of the original pin]

Projekt-Metadaten

Cat with Knife GitHub Repository

Schumi daniela.novac@betreiberverein.de

Steve Mayze smayze@yahoo.com

Logbuch / Schritte

Tag 1 Friday 07.02.2025

We discussed the design

[PHOTO of the model badge]

Tag 2 Saturday 08.02.2025

A PCB is made up of layers. These layers can be set up to create images by capitalising on the shading effect of each layer. This project was relatively simple in that the bulk of the form was one colour. The only special requirements were with the eyes and the knife blade. 

For any board the first thing to define is the edge-cut. This layer of the design defines the outside boundary of the board. Ideally this needs to be 0.5mm bigger than the actual image itself as this will define the path that the cutting tool will make to create the board shape. If the edge cut is too close to the actual outline of the image, then parts of the image could be cut off.

In the sketch below Steve put together some initial ideas on how he believed the layers could stack up.

Tag 3. 11.02.2025

Schumi created the graphic files required - Edge Cut, Front Copper, Solder Mask, Back Solder Mask. There was a bit of going back and forth between Illustrator and KiCad to ensure that we could create the desired effect. Rather than having the eyes as glowing discs, the intention is to have the eyes as glowing circles. To achieve this we needed to ensure that there was neither copper nor solder mask on both the front and back of the board where the eyes are. This then exposes the underlying, translucent substrate layer. This effect could be created by modelling the eyes in the front copper layer as shown in the image below.

Edge Cut	Front Copper

The above copper layer is not enough. We need to be sure that the black solder mask would not cover the eyes nor the knife blade. When designing a PCB, the font solder mask (the image below left) defines where the solder mask should not be applied. This ensures that the board substrate layer will be visible around the eyes and that the copper is exposed for the knife blade. During fabrication, the exposed copper will be coated with a solder layer. This will render the knife blade silver in colour.

The back solder mask (the image below right) also defines where there is no solder mask. The PCB design will ensure that there is no copper also at this position, exposing the underlying board substrate. This then will enable light from the LEDs to shine through the translucent substrate.

Front Solder Mask	Back Solder Mask

A decision needed to be made as to the size of the board. It is a two way decision - The size of the board can dictate what parts to choose based on their size but also the requirements of the project can be that certain parts are unavoidable so the board must be big enough to accommodate these parts. In our case, it was thought to use reverse mounted LEDs This would not have been a problem but a further requirement was for blinking LEDs. The sourcing self blinking reverse mounted LEDs was problematic. It could have been possible with more electronics but time constraints meant we needed a simpler solution. It was decided to use 3mm self blinking LEDs, that could be bent into position behind the eyes. The next problem was the power source. This would also be the largest part on the board. The smaller holder for the battery series CR 1216, 1220 and 1225 was chosen. Along side the smaller battery holder, a small slide switch was chosen. Using self blinking LEDs with such a small battery cell makes the design relatively simple. i.e. there is no need to provide any current limiting resistors.

An additional place was made on the board to be able solder on a butterfly-pin so that the badge could be easily fixed to clothing.

PCB design with front copper pour	PCB design without the front copper pour, showing the back copper.

3D view of the final design	3d view of the back side of the PCB

The design files were sent off for fabrication, selecting a board thickness of 0.8mm to maximise the amount of light able to shine through and a black solder mask to match the original badge colour. 

Tag 4. 28.02.2025

The boards arrived so they were unpacked immediately and one was assembled to see if there were any issues.

	For this build, 3mm slow blinking LEDs were chosen. Equally, any though-hold LED can be used.

It was noted that the pad intended for the butterfly pin was omitted from the board but it is definitely in the design files. There was not notification that Steve was aware of for the fabrication to omit this. Probably on the grounds that there was no electrical connection and that it was only a place holder and not a real part

It was discovered during assembly that the large round pad for the battery should be tinned with some solder. This will ensure that the contact is raised above the solder mask. Otherwise the battery will not be able to make a good contact.

The assembled parts with the LEDs bent into position