In the first entry, we introduced Seeed’s SMT Assembly line, and we took a look at the paste applicator, pick and place machine and reflow oven. You may think that’s all there is to PCBA but there is more. We will cover through-hole assembly and testing options here.
Through-Hole Component Assembly
To solder large volumes of through-hole components, assemblers traditionally used wave soldering machines that run the boards across a molten bath of solder. But this method may not be suitable for double-sided mixed assembly boards, and continuously maintaining the molten bath is both economically and environmentally inefficient. So, to solder the many connectors and pins that typically go into development boards, Seeed has opted for a selective soldering method.
Plugging Grove connectors into the Seeed Grove Mini Fan v1.1 boards
First, the through-hole components are inserted into the boards by hand. Then they travel into the selective soldering machine where the underside is automatically sprayed with a layer of flux where required. The boards are then flash heated to activate the flux and prevent thermal shock of the components before traveling into the main area of the machine.
This ominous-looking piece of equipment is the selective soldering machine
This selective soldering machine has a module that can move along 3-axes with a small solder fountain protruding at the top. The module is programmed to lightly touch and drag the mini solder wave precisely onto the through hole pins only, leaving the rest untouched.
Instead of an entire wave of solder, this selective method uses a tiny amount of molten solder that is continuously re-used, saving energy and reducing solder wastage considerably.
The selective soldering unit moves up and applies solder from below
The entire process can be monitored from a display above the machine
Perfectly soldered joints every time!
The result is consistently clean and precise through-hole joints and minimal flux residue.
For more complicated soldering requirements such as fine pitch or small package components, Seeed Fusion has a highly trained team of technicians available that can solder these by hand.
Inspection and Re-working
After all soldering is completed, each board is cleaned and again carefully inspected for soldering defects such as tombstoning or misalignment from the reflow oven. Any errors are identified, and the boards are sent to the re-working station to be corrected manually.
Technicians are on hand to do any touch-ups
After visual inspections are completed, other more in-depth tests are carried out if required. Seeed can arrange various tests including functional tests to ensure your device operates as expected, mechanical tests such as temperature and humidity tests, In-Circuit-Tests (ICT), AOI and X-ray inspections for example.
Choose functional testing and every board is tested
After testing is complete, final quality inspection (FQC) is carried out and then the boards are packaged and shipped off using express DHL shipping (free for all PCBA orders). With this express service, the package typically arrives in 1-2 days.
This article completes the tour of the Seeed Fusion assembly facilities and should give you a better idea of the entire process from plain PCB to package. If you liked this, you may also like the State of Electronics video on their tour to Seeed Studios’ assembly site. In the next article, we will cover how to prepare the BOM file to retrieve a quote from the online platform and give you some component sourcing tips.
Seeed Fusion PCBA can carry out assembly on any type of board with any surface finish; rigid FR-4, aluminium, flexible, Rogers, 4 layer, 8 layer, ENIG, OSP, etc. and can perform SMT, through-hole and mixed assembly from components as small as 01005 (0204) package size or 0.38mm pitch. Our facilities are entirely lead-free and IPC-A-610F compliant.
Pricing starts from $25 set-up fee and $0.01 to $0.30 assembly fee per component. Seeed Fusion offers various component sourcing options to suit your needs from reliable partners such as DigiKey, Mouser and Element14, to in-house stock from our Open Parts Library (OPL).
- 10% off all PCB orders
- $50 off PCBA orders over $100
- Over 400 OPL components are completely free
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