After a series of high end mobile device teardowns, I decided to explore something made under the constraint of cost. I also wanted to explore an item with more moving parts than the iPhone. My Logitech M510 wireless mouse presented itself as a perfect candidate.

This product currently sells for 27£ and can certainly be considered a high volume product. This means that each part must be absolutely essential and assembly must be able to be done easily and quickly in order to ensure costs are kept low.

The Logitech mouse features a fairly standard array of buttons: right/left mouse clicks, a thumb controlled forward/back button, and a scroll wheel that provides a down click as well as a side to side click. The side to side scroll wheel clicks allow you to push on either side of the wheel, tilting the wheel and performing a click. In using this mouse I found myself accidentally clicking the scroll wheel sideways instead of straight down, so more resistance could have been added to reduce the chance of mis-clicking sideways.

The body of the mouse features overmolded grippy TPE material on either side of the mouse and several different textures are used on the plastic shell components from glossy to slightly textured.

To access the internals I first need to find a way into the mouse. I remove the battery lid to search for screws or clips inside of the battery compartment that will let me disassemble the mouse. The battery lid slides into the main body and uses a snap fit tab for retention. The square raised houses seen on either side of the lid (bottom right) are undercut, meaning a slide would have been needed during the injection molding of this component. These houses are used to retain the lid in place on the mouse. I eventually find two screws hidden under a plastic strap that is used to facilitate battery removal (left image).

With the two screws removed, I am able to pull up on the battery compartment which separates the mouse slightly (shown below). Next, I slide the battery compartment backwards and the mouse separates into two pieces: the top shell containing all the mouse’s buttons, and the mouse base which contains the PCB, scroll wheel, and battery compartment. I’ll treat each piece as it’s own teardown at this point since they are two distinct assemblies, and I’ll begin with the shell.

Shell Teardown:

The shell of the mouse is comprised of 5 individual parts that are screwed together and/or held in place with snap fits. Snap fits provide a quick, easy, and cheap way of connecting components together. They can be molded directly onto existing parts, remove items from the BOM, and take less time than screws to assemble. The downside being they can be difficult to disassemble for maintenance or repairs (not always the case) and are not typically as strong as a screw.

After unclipping a clear part from the center of the part and undoing 5 screws, the mouse shell comes apart into the 5 components described here. From left to right:

• Mouse Top Cover / Mouse Buttons: This part uses the elastic properties of the ABS plastic to incorporate the left and right mouse click buttons into part of the mouse shell cover. The part features 4 snap fit hooks, several stand offs, two screw bosses, as well as two square housings at the tip of each button used to retain the left/right click buttons on the mouse.

• Main mouse shell: Features 7 screws bosses which do not contain inserts (See iPhone 3GS), instead relying on self tapping screws to cut into the plastic bosses on installation. Not as robust as using inserts, however its cheaper and if you aren’t expecting large pull out forces or frequent disassembly, it’s a good cost down. This part has a ton of features, many of the squarish holes we see on the bottom half are for the mouse top cover’s snap fit hooks to clip into.

• Indicator light pipe: Simple transparent, probably polycarbonate, part that clips into place with three snap fits hooks molded into the main mouse shell. Its not easily visible (better shown in the image below), but this part extends from the top of the shell (where its snapped in place) down to the main circuit board. It’s purpose is actually to route light from an LED on the main logic board up to the top of the mouse. Interesting! Instead of positioning an LED on the top of the mouse and routing wiring to it from the logic board, this plastic part pipes the light up to where it needs to be.

• Side Thumb Button Stiffening Bracket: This bracket screws onto the main mouse shell with two screws and basically serves to add stiffness between the two side thumb buttons to prevent both buttons deflecting when one is pushed.

• Side Thumb Buttons: This single part is comprised of two cantilevered buttons and screws on to the main mouse shell with two screws. When either button is pressed the cantilevered arm deflects and contacts a switch on the mouse PCB.

Look at all those features! The three screws seen in the image below hold the side thumb buttons and button stiffener in place. It’s hard to make out but just to the right of the middle screw there is a vertical plastic rib. This rib is part of the button stiffener (below right) and is pressing onto a plastic tab between the two buttons (below left). This allows each individual button to deflect without the other moving as much.

With the shell torn down to its individual components, I set my attention to the mouse base and PCB assembly.

Mouse Base and PCB Assembly Teardown:

The base of the mouse is where the brain, power supply and scroll wheel are located.

As shown in the shell teardown, the mouse has 4 button inputs: left and right mouse click buttons, and two thumb click buttons. Each of these is a cantilevered plastic button which when pressed deflects and clicks a switch fixed to the main PCB. Below we see two black rectangular components on either side of the scroll wheel and another two green and white rectangular components to the right of the battery compartment. These are standard off the shelf components from Kailh as are the tactile switches on either side of the scroll wheel.

The scroll wheel is held on by a single point. There are two snap fit components molded onto the plastic mouse base that hold a plastic shaft on the front of the scroll wheel. This configuration allows quite a bit of movement from the wheel which allow the part to travel down, and tilt from side to side. We can see two arms extending in front of the wheel which rest on tactile switches. These are what is responsible for registering the side to side clicks. Behind the wheel there is another tactile switch which registers the down clicks. Interesting design!

With the wheel removed we get a better look at the three tactile button configuration and the two snap fit tabs which hold the wheel in place. We also see two sensors that are on either side of the wheel: a clearish white one and black one. These are actually what register the scroll of the wheel. They use a laser which passes through the spokes of the scroll wheel to measure the scroll rate and direction.

A better view of the wheel itself. The tactile “click” feeling from the scroll wheel is provided by a torsion spring pressed against the inner surface of the wheel. This inner surface is made with multiple flat surfaces instead of being completely smooth and round which causes the “click, click, click” as the wheel is turned.

The poorly photographed battery compartment slides into the mouse bottom assembly and clicks in place with another cantilevered snap fit tab.

Next the PCB is removed. It’s held in place with a single screw and several snap fit tabs. Even without the screw, the various locating features and snap fits hold the board in place quite well, the screw really just serves to eliminate any potential rattle.

And with that we’re done! The entire mouse is comprised of 11 components, 8 screws, and a PCB. There is a bit more that could have been removed from the wheel and battery case, but I did want to continue using this mouse. The amazing thing about this product is how well each component is self fixtured in place with different locating features and snap fits. Theres an absolutely minimal amount of screws used to assemble this and yet the product feels solid and cohesive when assembled. In addition, I think I could assemble this product from its state below to the finish item in under 60 seconds. It’s very well designed for assembly.