Prototype Assembly Methods

A high quality solderpaste print is not only important in a PCBA production environment but also for the manual assembly of prototypes.   I´m doing manual assembly for almost all of my PCB prototypes. In my experience, good solder paste printing is the key to making this process hassle-free and ensuring that no rework is required. Using a high-quality solder paste such as Loctite GC10 with a particle size classification of T4 or T5, even the assembly of fine-pitch components such as 0.4 mm WLCSPs and passive components down to 01005 is no problem. So far I have had fewer problems with hand-assembled prototypes than with factory assembled prototypes due to misplaced components or short circuits. This and the significantly faster availability compensate for the labour time that has to be invested in manual assembly. On top of that, it's a great exercise in the use of soldering tools, which is essential for any electronics designer.   For 0201 passives and smaller I´m using a round aperture in the solderpaste layer. This ensures that less solder paste sticks to the stencil when it is lifted off the board due to the reduced surface area of the stencil walls. By combining round apertures with a small stencil thickness very fine pitch component can be assembled. (The stencil print shown in the attached images was done with standard square apertures)   These are practices that I only use for manual assembly. The correct dimensioning of stencil openings and solder paste types according to IPC standards is the responsibility of the PCBA supplier for mass production.   #electronics #design #soldering #manufacturing #prototype

10 Tips for a successful prototype assembly day: 1. Organize and Label your fasteners - I put the screws into Agro drawer bins, and put the McMaster hardware label onto the bin... I keep all the hardware together in the center, for easier access. This is faster than dealing with opening/closing multiple sizes of bags and boxes. Plus, once a bag is slit open, it tends to dump all over. If you have several, similarly sized screws, consider consolidating them in the design. If it's hard to keep them straight in prototype assembly, it will be difficult to keep them straight in production also. 2. Order a pair and a spare of your prototype parts (order more parts than you think you'll need) it's unavoidable, things will break, or you'll strip a hole, or you'll want to test rework on one part before you do it on the real one... reasons go on forever. Just order a few more. If you need one, order 2-3 if you need 3, order 5-10. This obviously only applies to reasonably-priced parts. If a part is 20% of your prototyping budget, it's tough to order too many spares. If that's the case, be careful with that part! 3. Make sure you have enough fasteners. It's frustrating to be in the middle of assembly, only to run out of $0.10 screw, forcing a run to the hardware store (and good luck finding plastite screws or obscure shoulder screws at Ace) Fasteners are cheap, throw in a few extra bags with your McMaster order. It's better than stalling out in the middle of the build. You'll use them eventually. If your development is so cash-strapped that you can't order extra screws, maybe reconsider the viability of the program. 4. Dry test fit before doing anything irreversible. If you're going to modify your parts (*no going back), make sure that you understand what other parts will have to change. Think about changes that can be reversible, or how you might fix if your dremel slips, or the part cracks. Have a backup plan for when rework goes south. 5. Seasonal changes: In winter time, SLA parts get really brittle. Be careful, and let parts come to room temp before handling. In summer time, humidity can affect parts, especially nylon parts. 6. Check your BOM and make sure EVERYTHING is on order, don't let the 'golden screw' hold up the entire assembly process. Wiring harnesses, connectors, labels (if critical), etc. See Number 3. 7. Document everything. Write down everything that you notice. What needs redesign in the next rev? What assembly issues did we run into? What needs more clearance? 8. Keep a 3D printer ready and waiting, you'll almost certainly be reworking parts on-the-fly. 9. Photograph each step for building assembly instructions, or for showing your team how it goes together. You don't want to be the only person that learns from this process. Videos of assembly are even better than pictures. Talk your way through the recording, taking note of anything that should be documented later. Have someone (or AI) transcribe the video for future use.

This is the single best method for producing production-grade prototypes Yet many designers have never heard of it. Vacuum or Polyurethane casting is a process where a master pattern is reproduced using a silicone mould tool. Did you know this can be done entirely in-house? The benefits are clear: - Excellent surface finishes - Undercuts allowed - Rigid & elastomeric materials - Great tolerances - Low-cost tooling Check out my 10-step guide to master vacuum casting in-house. Each step has a handy graphic to make it as clear as possible. In this complete design guide, I cover when to use vacuum casting, how to overmould, how to add threads and how to work with tight tolerances. Included are 3 graphs that compare the cost & and lead time for the top 4 rapid prototyping methods. Check it out: https://lnkd.in/e3i53ybx It took me three months and £3000 in materials and equipment to find the perfect method for reliably creating accurate polyurethane prototypes. With this guide, it should only cost around £400 in materials and equipment. Just remember to be patient and enjoy the process! 𝐅𝐨𝐮𝐧𝐝 𝐭𝐡𝐢𝐬 𝐮𝐬𝐞𝐟𝐮𝐥? 👍 + Share with your network to help them master DFM + Sign-up to our bi-weekly DFM newsletter: https://lnkd.in/g8AQHCGJ + Follow me for more Design for Manufacturing (DFM) content. Our mission @ Dezarc is to take the guesswork out of material selection by supplying designers & engineers worldwide with material sample kits. #manufacturing #productdesign #design #designengineering #dfm