Firefly Design LLC

Product Design Consulting

Firefly Ice: Production: Final Assembly

Final assembly involves attaching the battery, PCBA, and the three plastic parts.  It is pretty straight forward, but there is some paint, tape, solvent, and glue involved.  The walk through below has a couple of tips to help learn the process.
Prepare the Top Plastic Part
The top plastic part has 6 light pipes where the LEDs shine through.
To mix the colors a thin layer of translucent white paint is used.
Apply a small amount of paint with a toothpick to each of the light pipes.
Make sure there are no bubbles in the paint, then wait for it to dry.
Assemble the Top & Shell
The shell and top piece are press joined together into a single part using a polycarbonate solvent.  There are 3 small alignment features on the shell and top piece.  The single light pipe lines up with the USB opening.  Align the two parts carefully.
Press the top part into the shell.
Check that the parts are aligned properly, the alignment features are interlocked, and the top is pressed all the way into the ring.
Apply thin polycarbonate solvent, such as Weld-On 3 or 4, inside the ring where it meets with the top piece.  It should flow into the seam and form a strong bond.
Allow the parts to harden completely before continuing.
Battery Attachment
The battery wires are soldered to the back of the PCBA.  Be careful to solder the wires to the correct pads (do not reverse them).
First solder the black (negative) wire to the pad on the right as shown below.
Next solder the red (positive) wire to the pad on the left as shown below.
Attach the Battery to the PCBA
The battery is attached to the PCBA using double sided tape.  Cut a small square of double sided tape and attach it to the battery.
Peel off the back and press the battery into place on the PCBA.  The battery should be located as shown below.  It should be clear of the post holes near the USB connector, while staying close to them so that the battery does not go into the antenna area on the opposite end of the PCBA.
The wires should be folded at the middle as shown below.
And then folded over near the top of the battery where the battery protection circuit is.
The PCB can now be placed into the top shell assembly.
Back Assembly
The back piece has a snap fit feature and will snap into place.  It is also glued to the shell for extra holding strength.
Apply glue, such as Weld-On 16 thinned with Weld-On 3, around the USB connector to make a splash proof seal.
Apply glue to the mating posts.
Apply glue to the snap fit area inside the shell.  Be careful not to get glue on the exterior cosmetic surface.
Place the back piece in as shown with the wires on the inside of the posts.  This makes sure that the wires will not be pinched under the supports on the back piece.
Now lower the other side of the back piece into place.
Apply light pressure to snap the back into place.  Pressing too hard can push the back in too far, so be careful with this step.
Wait for the glue to bond to maximum strength and your device is complete.