JLC Assembly - stencil weirdness with non-component pads - Page 1
Forum section: electronics / general

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 30, 2024, 11:30:52 pm
content: My PCB has some non-component pads that I want paste on, so wires can be soldered on later - no problem I thought, just put a pad with an an aperture in the paste layer, like any component pad, and put a note in the comments box as I'd seen something about pasted non-component pads somewhere on their site.I got a message from JLC that they don't use the customer's paste gerber file, and create the stencil from the component footprints - can I send a drawing showing which non-component pads need paste..?And of course they add a cost supplement for this - $3.20 (Is it really worth bothering to bill for such a small amount?)Out of curiosity - for anyone that's used JLC PCB assembly and had parts that were not populated - were the pads for the non-fitted parts pasted or not ?

author: coppercone2
author_rank: Super Contributor
timestamp: October 30, 2024, 11:38:34 pm
content: it sounds like a big hassle maybe its worth just spring connectors on there , or something like thishttps://mac8usa.com/product/lever-type-electric-wire-installation-terminal/I have a feeling that some how through translation problems or just general negligence your gonna get screwed on thisI think their cheap because its super structured and automated, i don't think its go-getters

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 30, 2024, 11:59:00 pm
content: Quote from: mikeselectricstuff on October 30, 2024, 11:30:52 pmThe handful I've done did not have any paste on non-fitted part pads. My boards were all HASL, but even the larger pads (like the EPAD for a QFN) were flat so I'm fairly sure they didn't apply paste there.

author: langwadt
author_rank: Super Contributor
timestamp: October 31, 2024, 12:08:03 am
content: Quote from: radar_macgyver on October 30, 2024, 11:59:00 pmmakes sense for people that want to source and mount some parts later

author: fourfathom
author_rank: Super Contributor
timestamp: October 31, 2024, 01:49:41 am
content: Quote from: mikeselectricstuff on October 30, 2024, 11:30:52 pmI've also had no paste on the non-populated parts. These parts were not included in the BOM, or (as I recall) the placement file.

author: Chalcogenide
author_rank: Regular Contributor
timestamp: October 31, 2024, 07:14:37 am
content: I have never asked JLC to put paste on non-populated components, but there is a specific drop-down menu in the "Advanced options" in the "PCB Assembly" section during ordering that is "Add paste for unpopulated pad & step stencil opening" that is "No" by default, but can be set to "Yes" or "Step Stencil Opening" - the catch is that neither option is available for the "Economic" PCB assembly.

author: Zoli
author_rank: Frequent Contributor
timestamp: November 03, 2024, 02:56:33 pm
content: Quote from: mikeselectricstuff on October 30, 2024, 11:30:52 pmAdd a test point with the desired shape and layers, and you're set.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 03, 2024, 04:23:55 pm
content: Quote from: Zoli on November 03, 2024, 02:56:33 pmNo - they only put paste on parts they will be assembling, they ignore your paste gerebr.I can see maybe this makes sense as they prefer to use their own paste apertures to avoid assembly issues caused by random customer aperture sizes.

author: Zoli
author_rank: Frequent Contributor
timestamp: November 03, 2024, 05:07:28 pm
content: Quote from: mikeselectricstuff on November 03, 2024, 04:23:55 pmThe paste cutout should be present both in the solder mask and paste layers; it is?Side note: test point can be considered component, so less excuse for them not to add solder paste..

author: langwadt
author_rank: Super Contributor
timestamp: November 03, 2024, 07:39:32 pm
content: Quote from: Zoli on November 03, 2024, 05:07:28 pmwhy would you want solder paste on test points?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 03, 2024, 08:08:19 pm
content: Quote from: Zoli on November 03, 2024, 05:07:28 pmUnless it's a physical part they are placing, they don't put paste unless you specifically ask them to

author: phil from seattle
author_rank: Super Contributor
timestamp: November 10, 2024, 07:14:46 am
content: Quote from: langwadt on November 03, 2024, 07:39:32 pmThat was my question, too. I'm doing this in a design right now. I don't need solder paste on them, I'll just hand solder a bodge wire if needed. I created a single pad part but excluded it from the BOM so it just shows up in the gerbers.

author: jduncan
author_rank: Regular Contributor
timestamp: November 10, 2024, 12:14:22 pm
content: Their assembly is so cheap (basically free), because it's HIGHLY automated and they're trying to minimize human touch:So it makes that they want to drive stencil generation from their own code which can verify correct aperture for exactly the parts they are going to place. Otherwise Joe Hobbyist with his random Eagle footprint library will come along and their PNP is trying to spit chips on bare pads (and of course then they'll get blamed for the fuckup).