TIRF LED and temperature control assemblies

Heat sink and LED mounting assemblies. These are installed into the main body.

Introduction

The TIRF LEDs and heaters are mounted directly to heat sinks, which do double duty: they both dissipate heat from the high-power LEDs and maintain a consistent temperature when the sequencing reservoir is inserted into the main body.

You will need to assemble four LED boards per unit:

  • Two for UV cleaving
  • One for the red and orange LEDs
  • One for the green and blue LEDs

Parts List

4x Heat Sink (Machined)

Model located inside the Main Body assembly

Optical Imaging

  • 1x each Edmund bandpass filters: 675/50nm (#86954), 625/50nm (#86953), 575/50nm (#86952), 525/50nm (#86951)
  • 1x filter holder (3D printed, see CAD file)
  • 1x Long working distance 5x LM Plan Achromatic Objective lens (BoliOptics, MT05073231)
  • 1x SONY IMX183 CMOS camera (Vision Components)
  • 1x Thorlabs Objective adapters (SM1A3)
  • 1x Thorlabs 1” adjustable lens tubes (SM1V05)
  • 1x Thorlabs 1” lens tubes (SM1L10)

LED

  • 4x MK 3 Heatsinks (See CAD file)
  • 2x visible LEDs boards (See pictures)
  • 2x UV LED boards (See pictures)
  • 1x each four color visible LEDs (LUXEON Rubix Color Line LEDs, MFG P/N: L1RX-L1RX-RED1000000000, L1RX-PCA1000000000, L1RX-GRN1000000000, L1RX-BLU1000000000)
  • 16x UV LEDs (Light Avenue: LA UY20WP1)
  • 4x 33Ohm UV LED current limit resistor (DigiKey: ERJ-P08J330V)
  • 2x 1 Ohm 3/4W SMD 1206 visible LED current limit resistor (DigiKey: SR1206FR-7T1RL)
  • 1x 1.27 Ohm 3/4W SMD 1206 visible LED current limit resistor (DigiKey: CRCW12061R27FKEAHP)
  • 1x 1.8 Ohm 3/4W SMD 1206 visible LED current limit resistor (DigiKey: CRCW12061R80FKEAHP)
  • 26 Gauge Enamel Wire
  • 30 AWG flexible silicone tinned copper wire (Fermerry)
  • 4x Molex FFC/FPC Jumber cables (Mouser P/N: 538-98267-0711)
  • 8349TFM Thermally Conductive Adhesive (One syringe of 8349TFM-A and one syringe of 8349TFM-B)

Other Mechanical Parts

  • 4x 4.7 Ohm 16W 1% 2512 SMD Resistor (Mouser P/N: 754-CPA2512Q4R70FST)
  • 1x NTC Thermistors (Vishay BCcomponents: NTCLE413)
  • 4.8mm diameter clear 3:1 heat shrink tubing 10mm long
  • 1x 10K Precision Epoxy Thermistor - 3950 NTC (Adafruit 372)

Assembly Instructions

LED Board Soldering

  1. The LED Board Soldering picture shows the PCB for visible LEDs. First, clean the board and apply a thin layer of SAC305 solder paste (Mouser #910-SMD291SNL250T5). Using a stencil is recommended.

  2. Place the LEDs (Red with PC Amber, Green with Blue) and the current limiting resistors (Red: 1.8 Ohm, PC Amber: 1.27 Ohm, Green: 1 Ohm, Blue: 1 Ohm) at the location shown below

  3. Heat the board to 250-270C, the solder paste will melt and the LEDs and the resistors will be well attached. Use the tweezer to adjust the position if needed.

LED Board Soldering

  1. The UV LEDs were connected in series (four as a set) by wire bonding.

  2. Carefully solder the silicone tinned copper wires to the bottom of the PCB

LED Heatsink Preparation

  1. Prepare a pea-sized volume of 8329TCM Thermally Conductive Adhesive by thoroughly mixing one half-pea-sized ball of 8329TCM-A and one half-pea-sized ball of 8329TCM-B. Spread a thin layer of the prepared 8329TCM over the Mk3 heatsinks, on the face that has the LED board seating area, in the region marked below. The layer should be roughly the thickness of a few pieces of paper

Attach an LED PCB to a heat sink

  1. Place one of the visible LED boards (Either the Amber + Red board, or the Blue + Green board) onto the prepared surface. Make sure the board is well-aligned with the side fins and the center pin.

  2. Press the stack together either by a press or by hand.

  3. Repeat steps 1 through 8 for the rest of the visible and UV LED boards. It will take 24 hours for the 8329TCM to fully cure. Heating up to 40-50C can slightly speed up the curing process.

Heater Cable Assembly

  1. Cut 2 lengths of 26 Gauge Enamel Wire roughly 50mm long. Strip one end of each wire segment, and solder the stripped end of each wire segment to one side of the underside of the 4.7 Ohm 16W 1% 2512 SMD Resistor

  1. Prepare a pea-sized volume of 8329TCM Thermally Conductive Adhesive by thoroughly mixing one half-pea-sized ball of 8329TCM-A and one half-pea-sized ball of 8329TCM-B. Spread a thin layer of the prepared 8329TCM over one of the Mk3 heatsinks, on the face that does not have the center ribbon cable groove, in the region marked below. The layer should be roughly the thickness of a few pieces of paper

  2. Place one of the prepared resistors, with the soldered face away from the heatsink, onto the bed of 8329TCM that was prepared. Press down on the resistor to ensure it is seated into the 8329TCM. It will take 24 hours for the 8329TCM to fully cure

Attach a heater to the heat sink

  1. Repeat steps 10 through 12 for the remaining 3 Mk3 heatsink

Thermistor Cable Assembly

One thermistor is used per unit to monitor the temperature of one heatsink, which is used as a proxy for the temperature of the sample.

  1. Prepare a pea-sized volume of 8329TCM Thermally Conductive Adhesive by thoroughly mixing one half-pea-sized ball of 8329TCM-A and one half-pea-sized ball of 8329TCM-B, and apply it to the thermistor.
  2. Dip the thermistor and adhesive into the cylindrical hole of one of the heatsinks. Historically, we have used the red/amber heatsink for this, but there is no reason to use one heatsink over another. It will take 24 hours for the 8329TCM to fully cure
  3. Splice female jumper cables to the other end of the thermistor cable.