Using Wedges of Solder Paste for better manual reflow @scalarelectric #Manufacturing

For fine-pitch leaded components, I'm seeing tremendous success with Wedges™ for manual-paste/place reflow.

cj at @scalarelectric posts on Twitter about using wedge-shaped solder-paste cutouts in their stencils:

For fine-pitch leaded components, I’m seeing tremendous success with Wedges™ for manual-paste/place reflow.

  • Increased gap between paste shapes
  • 50% reduction in total paste application
  • Occupies same rectangular envelope as default paste shape
  • Huge improvement in yield

Wedges™ for manual-paste/place reflow

I can see that it can increase the space between fine pitch pads. cj continues:

solder paste wedges

To get 50% coverage by way of EAGLE’s (design-wide) pad-shrinking rules would give you what’s shown on the right. Compared with 50% coverage by Wedges™ left. I do use pad-shrink almost everywhere, but for pads with high aspect ratios I think I prefer this bulkier shape.

If there was a way to set pad-shrink on a per-package basis (instead of per-design), I might do exactly that. But once you gotta go in and draw the art manually, the pad-shrink feature goes out the window.

cj continues: I tend not to have much of an issue with leadless packages using simpler paste art. The issue I see with leaded packages is that the high-aspect-ratio recommended footprints result in way too much solder going down, and all that extra solder ends up in undesirable places.

And I came up with the idea after building a proto with the default stencil artwork and getting an outrageous number of bridges.

This is that DF11, .5mm w/ Wedges, no mask between. No bridges, no opens.

This is that DF11, .5mm w/ Wedges, no mask between. No bridges, no opens.

cj later says: In my limited use of this technique so far (~150 joints), I’ve had zero shorts or other cause for rework. Compared to a previous attempt at assembling this design with the standard stencil artwork, where 5-10% of joints had issues.

I use it almost everywhere, but EAGLE’s “Perimeter Shave” pad-shrink technique struggles with high-aspect-ratio pads. To get (e.g.) 50% paste coverage you end up with paste apertures that are basically as long as your pad, but ~half as wide. Sometimes *very* narrow.

@ADSKEAGLE's "Perimeter Shave" pad-shrink technique struggles with high-aspect-ratio pads.

A final interesting discussion:

See the whole thread here.

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 16,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7:30pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org

Maker Business — How to start, manage, and fund a paid membership program

Wearables — Make a list of everything you want

Electronics — Design for test!

Biohacking — Vitamin-C + Gelatin for Accelerated Recovery

Python for Microcontrollers — Ports, app updates – CLUEs in the NEWs and more! #Python #Adafruit #CircuitPython @circuitpython @micropython @ThePSF @Adafruit

Adafruit IoT Monthly — Physical Event Notifiers, Particle deprecates Particle Mesh and More! #Adafruit #IoT @Adafruit @AdafruitIO

Microsoft MakeCode — Through the Classroom Door with LEGO Line Follower!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !

No Comments

No comments yet.

Sorry, the comment form is closed at this time.