This week, we’re very excited to bring you a special guest post by the good folks at Angaza Design! Headquartered in San Francisco with far-reaching operations in Tanzania, Kenya and Zambia, Angaza creates high-quality solar energy devices for the off-grid world.
Often times, especially if you’re just getting started, how your electronics lab is set up is overlooked. It’s most likely thrown together in an empty corner of a basement or garage with little to no consideration for how it’s organized.. Recognizing the importance of setting up and maintaining an ordered lab, Angaza has put together a thorough run-down of the tools, techniques, and tricks that have worked for them over the years. Of course, each lab will vary depending on the type of project and individual preferences but if you’re looking for a launchpad to get your workspace equipped and running, this is an excellent resource to kick things off with.
Download the pdf version of the guide here and get started!
Components of a Basement Electronics Lab
Your tweezers slip and another IC falls to the floor, where it instantly disappears into the dirty concrete abyss. Another IC forever mocks you from the crack between the tables. There are 1% and 5% resistors of three different footprints mixed together in the same bin. It’s difficult to keep track of all your parts when prototyping, especially when you’re part of a team in a small space. In this article, we’ll share our favorite strategies and products to accelerate the prototyping process, reduce part attrition, and increase lab feng shui. Welcome to the Electronics Basement at Angaza Design.
SMD Component Organization
Surface-mount and other small mechanical parts e.g., screws, washers, and pogo pins are the easiest to drop and the hardest to distinguish from each other. Keeping them separate but not wasting space was a priority for us.
The SMD component binders allow us to keep various SMD ICs logically organized in a space appropriate for their size. One possible scheme is to group each page by component type e.g., comparators, audio amplifiers, voltage regulators, diodes. The snap boxes, named for their Lego-like ability to be snapped together in different configurations, are used primarily for larger through holes and breadboardable items. Both are re-usable and the binder sheets and boxes can be separated to take to different parts of the lab. With proper care, we expect both of these solutions to save us space, time, reduce stress, and prevent us from over-ordering 1k resistors.
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Project and Equipment Organization
When dealing with multiple prototypes that use mutually exclusive sets of components, it makes sense to separate them from each other. When pressed on space, it also makes sense to group equipment types together for easy location. We find that ordinary, clear Sterilite bins and plastic shelving you can find at your local hardware store make it easy to store and access projects.
Just make sure to label the sides and tops of the bins so you know what’s inside! We label each box with part types e.g., “Soldering Equipment”, “Hand Tools”, “Shipping Supplies” or projects e.g., “Prototype A Testrig”, “Prototype R3.x”, “Raspberry Pi”.
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Organization and Visibility
The ability to properly examine boards in detail when troubleshooting a prototype or field failure can help you find hard-to-spot defects, such as solder bridges or floating pins. We use the following tools to enhance our vision in our basement lab.
- Magnifying Glass – A basic handheld magnifying lens is nice to have on hand.
- Magnifying Light – Just like the dentist’s office! Useful for close-up board examination, assembly, and rework.
- Workspace Lights – Depending on your lab configuration, this might not be as much of a concern, but we use bright LED lights to get adequate lighting in our basement lab.
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Soldering and Reflow
With the emergence of inexpensive PCB fabrication services like OSH Park and SEEED Studio, it often makes sense to send out early prototype PCBs and reflow them in-house. Sparkfun has a guide explaining the basics that is a good place to start. Below are the main elements of the soldering and reflow portion of our lab.
- Mylar or Polyimide Stencil (per PCB) – Essential for placing solder paste on a PCBA. A number of services exist, and we find OSH Stencils is a reliable choice that has a fairly quick turnaround time, and stencil prices under $20 for smaller boards.
- Solder Paste – This needs to be kept cool, and should not be kept in a refrigerator which also contains food.
- Solder Squeegee – If you order from OSH Stencils, they will include a basic paste spreader, which works fine for most cases.
- Toaster Oven – For reflow of early prototypes, a basic toaster oven works fine, and you can manually attempt to emulate a temperature profile. For a better reflow, there are options to modify existing ovens with temperature controllers, and inexpensive options like the Reflowster which make adding temperature control pretty easy. When selecting an oven, options like multiple heating elements and a circulation fan to prevent hotspots are definite benefits. Perhaps obvious, but the same oven shouldn’t be used to cook anything edible after using it for solder reflow.
- Cleaning Supplies – Get some compressed air to remove dust and small particles from housings, plenty of isopropyl alcohol (get it in the spray can) and some bristled brushes (soft brass) for cleaning excess flux or other residue from boards, as well as for cleaning up excess solder paste after a reflow. The alcohol also proves useful if you’re dealing with field failures or prototypes that might be exposed to dirt or grit infiltration.
- Hot Air Rework Station – Useful for removing or replacing SMD components. Be sure to wait for the solder to reflow before pulling the component—it is possible to lift a component along with its pads, particularly for smaller footprints.
- Soldering Iron – Find one that heats up quickly and maintains the temperature that you set. Make sure to get extra tips in smaller sizes for SMD work if you need them.
- Solder Tip Cleaner – Use this when the wet sponge is not enough to clean the oxidation off of a soldering tip.
- Solder Fume Extractor – An extraction fan with a carbon activated filter, to take care of the solder fumes.
- Safety Glasses – Similar to the extractor—please be safe and protect your eyes from splashing solder!
- Safety Gloves – Approved for handling food and solder paste!
- Flux Pen – Have this on hand for rework; apply flux to the solder before reflowing it.
- Solder Sucker/Vacuum – Does what the name implies—heat the offending solder, and use this to pull it up off of the board.
- Desoldering Braid [Optional] – Useful for removing solder where there is a risk of pulling up a pad or SMD component. Just press the braid to the solder, heat it with the iron, and let the braid wick it away.
- Panavise – Some way to hold a board in a convenient position while placing or removing components is essential. The model 396 opens extremely wide, but select one that has appropriate dimensions for what you plan on holding in it.
Order:
- WEP 858D Hot Air Rework
- Aoyue 937 + Soldering Iron
- Solder Tip Cleaner
- Solder Fume Extractors
- Safety Glasses
- Safety Gloves
- Flux Pen
- Solder Sucker
- Panavise Model 396
Tools and Bench Equipment
Most of our daily work deals with relatively low frequency signals. You will need additional equipment if you need to examine RF or wireless links.
- Bench Oscilloscope – A popular choice under $500 is the Rigol DS1102E. Make sure to consider the sample rate that you’ll need, depending on the circuits being scoped. If you end up going with the Rigol, check out this post showing some of the features (including long memory).
- Handheld Oscilloscope – The portability is convenient for field troubleshooting or taking a quick look at a unit under test, but it isn’t a replacement for a full bench oscilloscope. The DSO Nano is a popular option for this purpose.
- Multimeter – If you have the budget for it, go for a Fluke 87V as a good all-around DMM (digital multimeter). It responds quickly, has very accessible averaging and min/max holding functions, and is well built. For a review of some solid meters at a lower price point, take a look at the EEVBlog $100 Multimeter Shootout (or the $50 Shootout). In the Angaza lab, the EX330 and 87V see the most action. If you find that you need a multimeter to perform data logging, consider meters similar to the Fluke 289.
- Tweezer Multimeter Probe Leads [Optional] – These allow you to probe SMD components easily with your existing multimeter; standalone SMD tweezer multimeters also exist.
- Logic Analyzer – This depends on how extensively your projects are using standard communication protocols (I2C, SPI, etc). Having one of these will make debugging these digital interfaces much easier than using a scope. One solid basic option would be the Open Bench Logic Sniffer; if you’re looking for more features, consider the Saleae Logic series.
- ESD Mat – The goal is to allow any static charge to slowly dissipate to ground, to prevent damage to sensitive components (like the gates of MOSFETs or IC pins). Most devices have some level of ESD protection, but some ESD damage is not immediately apparent. Digikey has a guide on setting up a full ESD workstation that’s worth a look.
- DC Power Supplies – At least one, preferably two or more. Pick a unit with granular enough control that a given output setting is repeatable.
- Programmable DC Load [Optional] – These allow you to set a load with a constant current, voltage, or resistance, and will attempt to maintain that setting. Useful when trying to characterize battery discharge curves in various conditions or the response of a voltage regulator to differing loads.
- Digital Calipers – Great for sizing PCBs to fit snugly inside an enclosure.
- Alligator Clips – You’ll never have too many. Try to get a reasonable assortment of colors for easy identification during prototyping.
- Pliers – Needlenose often come in handy for holding wires or pin headers in place while soldering, or removing PCBs from the toaster oven after reflow. We occasionally use bent-nose as well.
- Rotary Tool – Useful to have for basic housing modifications. An inexpensive model from Harbor Freight with a decent cutting wheel can go a long way.
- Hot Glue Gun – Even a basic one will come in handy for securing wires on early prototypes.
- Face Masks – To prevent inhalation of airbourne PCB particles while grinding prototypes.
- Electrical Tape – Plenty of rolls, narrow enough to easily wrap wires.
- Heat Shrink – Better for sheathing wires than electrical tape; if you’re careful, you can use the Hot Air Rework Station to shrink this, eliminating the need for a second air gun.
- Kapton Tape – Basically, electrical tape that can handle high levels of heat. Useful for situations where environmental testing is too hot for electrical tape.
- Duct and Packing Tape [Optional] – If you often need to package and ship from the lab, having a ready supply of packing tape is required. We keep plenty of duct tape on hand as well.
- Tweezers [Set] – Primarily useful in placing SMD components.
- Voltage, Current, and Resistance Reference [Optional] – If you want to ensure that all of your multimeters are reasonably calibrated with respect to one another, something like this will be useful.
Order:
- DSO Nano
- Fluke 87V
- Tweezer Multimeter Probe Leads
- DC Power Supplies
- BK Precision 8540 150W Programmable Load
- Basic Rotary Tool
- Tweezer Set
- Face masks
- List of Useful EE Tools from LadyAda
Test Automation (Optional)
- Raspberry Pi / Arduino – Having a widely-supported, open-source platform that can be quickly repurposed is helpful if you need to run a variety of automated tests. We often use a Pi or Arduino (depending on the need) for environmental characterization, which requires several sensors and testing to be carried out over time.
- GrovePi – This is a Raspberry Pi port of the Grove System for Arduino, which is an extremely fast way to build up a basic sensor system for logging data, like what you’d use for a one-off weeklong stress test.
- Relays – Useful for programmatically cutting power to devices like heaters, lamps, or fans, which can come in handy while performing automated testing. They come in multiple varieties so be sure to understand the acceptable input voltage range of the relay which you plan to use.
- Other Sensors/Modules – Lux sensors, temperature sensors, current sensors, and relays are the most used in our lab, but there are plenty of other options to consider. Depending on your need, motion sensors, leak detection, flame detection, or a number of others might prove useful.
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Parts/BOM Management
If you plan on outsourcing production of PCBs through a contract manufacturer or by working directly with a factory, you will want to have a very thorough Bill of Materials (BOM) including the following information for each part: – Value – Tolerance – Applicable rations (is that 1uF 0805 50V capacitor X5R, X7R, Y5V or NP0?) – Form factor – Manufacturer – Bunnie Huang has an excellent and thorough post on his blog describing what to consider in more detail
If you’re developing a large number of project versions (and BOMs) for different projects all at once, it might make sense to move to a more integrated solution for BOM and parts management. One reasonable cloud-based option is Aligni. The feature we find most useful is an easy way to compare part changes from version to version of a project, as well as the ability to quickly see breakdowns of project cost by component type.
Aligni integrates with Octopart to provide realtime pricing (in various quantities) for any part, and integrates with S3 to provide storage for datasheets and design files which you might want to keep associated with a particular part or project. There are a variety of other helpful features, like the ability to track which parts can act as substitutes for others, purchasing and build tracking tools. If your work is open-source, you can apply for a free account through the “Open Aligni“ program.
Operations/Ongoing Maintenance
Small actions on the day-to-day can add up to a lot of work over time. A few of our favorite operational practices are shared below. – When receiving inventory, adjust inventory levels at the time of receipt – Consume inventory at the time of a build to keep levels accurate (Aligni does this automatically if using its build management features) – Consider a 10-minute cleanup session at a set time every day to battle daily clutter – If you work with batteries, consider rigging up a battery charging station early on to keep a bank of fully-charged batteries for testing – Set aside a bin for all e-waste you generate and take care of it responsibly!
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