M2Slim Install Guide

Step 4: Soldering

Overview

While the soldering for this mod is not recommended for beginners the design of the flex PCB pads and cutouts have been optimised to make soldering as easy as possible.The biggest concern when soldering will be avoiding overheating the flex PCB as it is made of plastic. For this reason a temperature controlled iron is required, preferably of the cartridge type (such as Hakko T12 or JBC C245).

Temperature

As a general rule I try to keep contact with the flex PCB at 1-2 seconds at a time regardless of temperature to avoid overheating. This should not be an issue if you are using flux.The manufacturer does not recommending going above 260C but this is likely for longer durations in a reflow oven. I have tested going up to 320C using leaded solder without damage but staying around 230C-240C is easy with flux and leaded solder. Lead free solder requires at least +30C higher temperatures which may make thermal management harder.Feel free to increase the iron temperature to 300-340C when soldering to the ground plane of the PS2 to compensate for the large thermal mass. Struggling with a low temp is ironically more likely to cause damage than a short burst of higher temperature.Since the PS2 likely uses unleaded solder mixing in lead may cause issues over time. However lead free solder will require higher temperatures. The most optimal method may be to desolder the factory solder using wick and replacing with it leaded if you are concerned with an unknown mixed alloy.

General Soldering Tips:

Clean your iron using the brass wool between every pad.Apply a small amount of solder to the tip before touching the pad to allow solder to flow it to create the joint.If you have issues with solder bridging between contacts such as those on the resistor arrays, use a clean iron tip and flux to try and remove some of it before attempting de-solder braid.While I have used braid without issue there is a higher risk of damage due to the heat involved.

Tools:

Required:

  • Temperature controlled soldering iron

  • Brass wool tip cleaner

  • Solder

  • No-clean Flux

Recommended:

  • Multimeter

  • Tweezers

  • Good quality desolder braid

  • Torch or magnifier to assist inspecting solder joints

Kit parts:

  • M2Slim adapter

  • 1x 50Ω 0805 Resistor

  • 2x Yellow 0805 LED

  • Kynar wire

Optional Parts:

  • 4x 100pF 0805 Capacitors (Not reccomended)

Step 4.1       Remove LED board from main flex

  • If your flex cable has the LED board attached, carefully remove it using scissors or ruler and knife.

  • Take care to not damage the main flex.

Step 4.2       Solder resistor to M2Slim

  • Tin one of the pads.

  • Using tweezers to hold the resistor in place use your iron to solder it into place.

  • Solder the other pad.

  • I recommend leaded solder and ~270C iron temp.

Step 4.3       Clean PCB for soldering.

  • Clean the area around the IDE pads on both sides with a safe solvent like isopropyl alcohol or denatured ethanol.

Step 4.4       Bend flex cable.

  • Carefully bend the flex cable as shown.

  • Do not crease or form sharp bends as this can break the traces.

  • Solid lines indicate the inside of the bend.

  • Dashed lines show the outside.

Step 4.5       Prep power pads

  • Gently scrape the ground via to expose fresh copper.

  • Tin ground via

  • Tin 5V pad

  • The data pads will be prepared later.

Step 4.6       Test fit flex cable

  • With the M.2 connector facing down, align the flex cable cutout and pads with the 3 resistor arrays near the edge of the board.

  • Make note of where the two ground pads on the flex PCB line up with the exposed copper ground plane of the PS2.

  • The flex cable should lay perfectly flat against the PS2’s PCB.

Step 4.7       Prep data and ground pads

  • Apply flux to the resistor networks and 4 unpopulated pads.

  • Apply flux and then tin the exposed copper area of the board.

Step 4.8       Align and tac down with solder

  • Carefully align the pads again and solder a pad at each end of the resistor arrays to tac down the flex cable.

  • A temperature around 270C is recommended.

  • Apply a small amount of solder to your iron and let it wick into the pads.

  • The flex cable should lay perfectly flat against the PS2’s PCB.

Step 4.9       Continue soldering

  • Solder down the grounding points to secure the flex PCB in place.

  • First tin the flex at a 270C then increase temperature to 320C to heat the ground plane.

  • Solder the 5V and GND pads.

  • Increase temperature above 270C if these pads do not flow well.

Step 4.10       Inspect the solder joints

  • Use a light source and magnifier to inspect each solder joint for shorts or poor connections.

Step 4.11       Flip board over

  • Hold the M2Slim adapter and carefully flip the board over.

Step 4.12       Prep underside pads

  • Flux and tin the 3 vias.

  • If your vias are covered with photomask you will need to gently scratch it off to expose them.

  • Apply flux and fresh solder to the pads.

  • Flux is usually enough for the resistor array.

  • Tin the exposed ground plane as shown.

Step 4.13       Align and solder pads

  • Align the 3 tinned vias with the 3 holes in the flex cable.

  • Tac the cable into place using some of the larger pads you tinned earlier.

  • Solder the vias.

  • You should not need to add more solder. Just touch the pads with a clean iron.

Step 4.14       Finish soldering the underside

  • Solder the other pads and resistor array.

  • Solder the ground pads to provide strain relief and support.

  • Double check that all pads, vias and resistor array for shorts or poor connections.

Step 4.16       Prepare the activity LED board.

  • Use a small piece of tape to hold down the activity LED flex.

  • Use tweezers to remove to plastic film on the LED tape.

  • Take care not to lose the LEDs. It would be smarter to take them out one at a time rather than dumping them out as shown.

  • The flex is very thin and soldering to it will burn the surface underneath. I used some spare cardboard to protect my desk.

Step 4.17       Solder the top LED.

  • Align the polarity mark with the closed end of the white silk screen marking on the flex.

  • Apply solder to one of the pads.

  • Placing the LED on its side as shown hold it against the solder blob and use your iron to reheat the joint.

Step 4.18      

  • Solder the other pad as normal.

  • Use your finger to hold down the flex and peel the tape off from both the work surface and the flex.

Step 4.19       Solder bottom LED

  • Flip the flex over and use the tape to hold it down.

  • Tin one of the pads.

  • Remember to align the polarity mark with the silk screen.

  • Holding the LED vertical (pointing up) solder it to the pad by reflowing the tinned pad.

  • Solder the other pad and remove the tape.

Step 4.20       Test LED fitment.

  • Place the PS2 board back into the lower shell.

  • Place the LED flex roughly in the location shown.

  • Check that there is clearance between the flex and the case.

  • You may need to trim the flex to make room.

  • This board has a large amount of solder on the USB port which will be removed.

Step 4.21       Clean up USB joint [Optional]

  • Remove some solder from the USB port to make room for the LED flex.

  • Use a higher temperature (>320C) and flux to assist the solder braid.

Step 4.22       Prepare 5V via

  • Scrape away some of the soldermask in the area shown.

  • Tin the vias.

  • Clean up any mistakes, such as solder on the pad to the right, with braid. This is the main 5V rail so shorts must be avoided.

  • Flux residue can be cleaned with IPA or ethanol.

Step 4.23       Final fitment and trim

  • Once the final location of the LED flex is figured out trim the pad so that it does not over hang the 5V vias like shown.

Step 4.24       Solder LED flex

  • Tack the flex into place using the 5V vias.

  • A higher temperature (>320C) may be required to avoid a cold joint like shown in the photos.

  • Apply solder to the USB joint and flow it onto the mechanical pads on the LED flex.

Step 4.25      

  • Use some flux to help tin the bare copper on the PS2.

  • Flow the solder onto the LED flex.

Step 4.26      

  • Solder the jumper on the LED flex closed. This connects the top and bottom LEDs in series.

  • Tin the pad labelled C.

  • Remember to reduce your iron temp back down to ~270C.

Step 4.27      

  • On the main flex cable tin the pad with the negative (-) marking as shown.

Step 4.28      

  • Align the kynar wire as shown.

  • Try to route it around the chips and avoid the screw holes.

  • Mark the wire, cut it to length and remove the insulation from both ends.

Step 4.29      

  • Solder the wire to the pad labeled C on the LED flex and the (-) negative marked pad on the main flex.