• Finishing up DIYTIL305 1/2

    Mile03/27/2019 at 23:42 5 comments

    This is first of two final project logs to conclude this project. This log deals with redesign, assembly and testing of DIYTIL305 boards. Finished boards are shown later in the log. Second log will describe problems and things I learned working on this project.

    After making first version of DIYTIL305 (previous project log) I needed easy way to test those boards after assembly. Solution was "TIL305 Test board". Since I needed to order PCBs for different projects from fab house, I designed this test board to make life easier. Image shows original TIL305 displays being tested.

    Then I redesigned DIYTIL305 PCB to make assembly process easier (bigger led pads, adjusted solder paste expansion) and tweaked dimensions to mimic the original.

    Next up was assembly itself. First I made one display with red leds to see if changes to the new design are good. Success! First board passed the test with all leds soldered correctly. That meant I could move to other boards(colour variations).

    0201 leds are only available in red, green, white, blue, orange and yellow colours. I used all colours except yellow because it is not that much different from orange. White leds were hardest to place because they don't have transparent case, so they can't be visually inspected for correct orientation.

    Before proceeding to glueing displays together I cleaned PCBs of dust and flux residues using isopropyl alcohol and kimwipes.

    Polycarbonate filters(CR-39) were used as display covers. They were glued using 3M VHB 4910 double sided tape. Transparent, acrylic foam tapes are used where clear attachment of two materials is needed and therefore are ideal for this application.

    Glueing display covers was straightforward, but since I didn't have access to laser cutter I cut them by hand using box cutting knife(scoring and snap method). They aren't the prettiest, but for a few prototypes they are good enough.

    I made six displays in total. Now I just need project to use them on. Any suggestions?

  • Assembling DIYTIL305

    Mile10/25/2018 at 21:27 6 comments

    This week I assembled few DIYTIL305 modules. Main problems were: Solder paste that wouldn't go through stencil, leds sticking to tweezers and not being aligned with footprint after reflow process.

    First problem was solved by getting finer grain solder paste (in future led footprint will be adjusted). Solution for second problem was to clean tweezers with rubbing alcohol multiple times during assembly process and re-heating leds with hot air gun with addition of flux so they align with footprint (some leds are still misaligned). 

    Afterwards I did some comparison between DIYTIL305 with red transparent acrylic and original TIL305 (last two pictures). In those pictures DIYTIL305 consumed 1.27mA and TIL305 15.78mA.

  • Preparing for assembly

    Mile10/17/2018 at 22:27 2 comments

    DIYTIL305 is made out of three main parts:

    1. PCB - PCB is 0.8mm so that I can easier match TIL305 dimensions (PCB + diffuser). Kingbright APG0603 series of leds is used (0201 Imperial code). Black solder mask is used to provide better contrast of leds with background. Exposed copper traces on PCB as a throwback to original part.
    2. Pins - Machined header pins with broken plastic guard are used. Compatible with breadboards and IC sockets, cheap, accessible, gold plated. Also 1.27mm pin header can be used for lower mounting heights when soldered.
    3. LED Diffuser - Used to make the light from leds more uniform and distinguishable. I will approach to this from three different angles:
      • FDM printing using Red transparent filament (results showed on image below).
        • PROS: Cheap
        • CONS: Low quality of details, post processing needed(layer lines), limited selection of colors
      • SLS printing using transparent resins.
        • PROS: Great quality, possibility of replicating TIL305 diffusor in full detail
        • CONS: Expensive, limited selection of colors
      • Laser cut acrylic (suggested by Dave's Dev Lab). Example of acrylic that can be used showed on image below.
        • PROS: Cheap, Great details(sharp edges), vast selection of colors
        • CONS: Needs special mounting method(3D printed parts just clip on)
    • PCBs are arranged into 2x5 panel for easier assembly.
    • Mechanical prototype for pin header and diffuser testing.
    • Different types of diffusers are being tested.

  • This is TIL305

    Mile10/10/2018 at 21:45 4 comments

    According to datasheet dots on TIL305 are arranged on 0.05"(1.27mm) grid. With that information I can now measure the size of a single dot. On the picture below each increment of scale represents 0.1 mm. It means that single dot is 0.4x04mm. I thought incorrectly that they were 0.6x0.6 (drawing from datasheet is more symbolic than actual representation of the part).

    For my version of TIL305 I will use 0201 leds(0.65x0.35mm) rotated by 45° on 1.27mm grid.

    Display showed on pictures below has marking "KOREA 8418".

  • Before TIL305 there was TIL302

    Mile10/08/2018 at 17:14 0 comments

    While researching TIL305 I discovered TIL302. It shares same package as TIL305 but is configured as seven segment, unlike TIL305 which is 5x7 matrix. I had to get one so here are some pictures: