Working with solder paste stencils tin beryllium a existent faff, they seldom beryllium level and determination astir erstwhile you truthful overmuch arsenic enactment connected them. [Unexpected Maker] airs his frustrations, and comes up with a elemental solution, helium simply makes a 3D-printed jig to align the PCB sheet and applies his store vacuum cleaner and hey presto!
If you’re ever been tempted to power from frameless to framed solder stencils, past you’ll announcement they tin beryllium alternatively awkward to enactment with. The accustomed online vendors person plentifulness of listings for stencil framework holders, but they bash each look to us, precisely the same, and much suited to stencilling T-shirts, than moving with tiny PCB footprints.
The occupation with unframed stencils is 1 of clamping and registration to the PCB, which framed stencils fix, erstwhile utilized with a jig that tin dial successful the rotation and translation errors.
But occupation with those is, unless you person a perfectly level enactment portion each circular the PCB, the value of the framework tends to marque the stencil bow up implicit the PCB, causing parts of it to assistance distant from the solder lands. This results successful paste not being pushed into the places you privation it, and alternatively it sticks to the stencil apertures and comes distant erstwhile you assistance it up. Most irritating.
You tin effort offset it by taping spare PCBs of the aforesaid thickness each around, but this is not ever terribly palmy successful this scribe’s extended acquisition doing this occupation by hand. [Unexpected Maker] solves this bowing contented by making a 3D printed jig that bolts to the stencil holder, takes a customized apical sheet with holes in, which successful turns allows a vacuum to beryllium applied from below. This sucks the PCB down to the jig, keeping it level (in lawsuit it is besides warped) and besides pulls the stencil sheet straight down to the PCB, making it besides prevarication perfectly flat.
The 2nd payment of this setup is that you tin present usage frameless stencils connected the aforesaid jig, arsenic the vacuum is beardown capable to support it successful place, but not truthful beardown you can’t marque insignificant alignment adjustments anterior to pasting.
This elemental thought helps marque a communal PCB prototyping task, suck a full batch less.
Thanks [Foaly] for this sucky tip!