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alanbjohnston edited this page Jan 22, 2023 · 7 revisions

Building the CubeSatSim Pico and Solar SMD

These are the instructions for building the Pico Board and Solar Board as full Surface Mount Device (SMD) Boards

Here is the software for the CubeSatSim Pico: https://github.com/alanbjohnston/CubeSatSim/tree/pico/cubesatsim

Pico Board v0.5s

These are the instructions for building the Pico v0.5s board SMD Components.

Here is the Pico PCB v0.5s:

cubesatsim-pico-0 5s_top cubesatsim-pico-0 5s_bottom

The grey in the images indicates where solder paste is to be applied. Note that the Pico processor U1 is mounted on sockets, not SMD soldered, so no paste is applied to these pins.

The optional SMD components D5, J12, and LED6 - LED10 are not mounted, so no paste is applied to these pads.

You will need these tools:

  • Safety glasses (to protect eyes while soldering or trimming leads)
  • Solder Rework Station (a fine tip soldering iron and a hot air wand)
  • Fine solder
  • Solder paste
  • Reflow oven
  • Flux pen
  • Tweezers
  • Needle nose pliers (to bend leads and hold parts)

Assembly

The best way to do SMD soldering is to use solder paste with a stencil and run the board through a reflow oven. The instructions here will cover this approach.

An alternative approach is to solder each component individually with an iron or hot air. This approach is covered here for the v0.2 PCB: Pico v0.2 SMD Instructions

Stencil

Start with your SMD stencil setup. You will need three blank PCBs of the same thickness, a backing board, the metal stencil, and some tape to secure it all together:

IMG_6479

The PCB should slide in securely but not be loose. When the stencil is laid on top, you should only see the PCB pads. Apply the solder paste to the stencil and spread.

IMG_6480

Spread until all pads are evenly filled:

IMG_6481

Open the stencil and remove the PCB:

IMG_6482

Mounting Components

The components can be mounted in any order. Sometimes it is easier to attach the PCB to cardboard or a board so you don't have to touch the PCB to move it around.

Resistors do not have a polarity. Check resistor values before mounting and double check with a meter if you are unsure.

All capacitors except one do not have a polarity.

Some of the components have a polarity - those components will be shown here.

The polarity of diode D8 is indicated by a white line on the component:

IMG_6486

Here's how it looks mounted on the PCB:

IMG_6489

The polarity of diodes D2 and D10 is indicated by a white line on the component:

IMG_6490

Here's how they look installed on the PCB:

IMG_6498

IMG_6491

The polarity of the chip antenna E1 is indicated by the writing on it. The side closest to the Y of YAGEO should be on the left as shown here:

IMG_6503

The capacitor C2 has a polarity indicated by a bar on the component:

IMG_6504

The bar should face up on the PCB as shown here:

IMG_6506

The crystal Y1 has one pad which is notched as you can see from this view of the bottom:

IMG_6508

If you flip it upside down, it looks like this:

IMG_6509

It then mounts on the PCB like this:

IMG_6510

The SAW BPF also has one pad which is larger than the others:

IMG_6512

If you flip it over, it looks like this:

IMG_6513

Here's how it looks installed:

IMG_6514

The clockgen IC U10 has a dot marking pin one, which should be down and to the right:

IMG_6515

Be careful not to use too much solder paste otherwise the pins will be bridged. Here is how it looks installed:

IMG_6517

The SR_FRS FM Module U6 is difficult to handle since it is too large for tweezers. Also, try to align the pins with the pads. When mounted, it looks like:

IMG_6519

Here is the complete board:

IMG_6520

Here is the board after running through the reflow oven:

IMG_6523

Installing the Through-Hole Components

Finally, solder the through hole components including:

IMG_6538

  • Red, Green and Blue LEDs: LED5, LED3, LED2, LED1, LED 4.
  • Stacking GPIO header J1 (mounted on the bottom of the PCB)
  • Female sockets 1x20 for the Pico U1
  • Female socket 1x8 for the BME280 J3
  • Female socket 1x4 for the MPU6050 J2
  • Switch S1
  • RBF Switch X1
  • Female socket 1x8 right angle J4 (mounted on the bottom of the PCB)

Once all these components are installed, the board can be powered up via the Pico micro USB and you should see the red and green LEDs on, the blue LED come on when transmitting.

IMG_6551

Note that if you have a Pico W, you will not see a green LED blinking on the Pico.

With power to the USB-C connector on the top, with the RBF 3.5mm plug installed, you should only see the red LED on:

IMG_6554

With the RBF plug removed, you should see all the LEDs as before:

IMG_6553

Solar Board v0.3s

Here is the Solar PCB v0.3s:

cubesatsim-solar-0 3s_top cubesatsim-solar-0 3s_bottom

Start with the stencil and apply solder paste:

IMG_6618

IMG_6620

Here's how the board looks with solder paste applied: IMG_6625

Resistors and capacitors on the board do not have any polarity.

The diodes have a bar to indicate polarity:

IMG_6626

Here's how they look installed with correct polarity:

IMG_6627

The INA219 ICs have a bar to indicate the side with pin 1:

IMG_6629 2

The PCB also has a bar to indicate pin 1, for example here:

IMG_6630

Here's how all the ICs look installed:

IMG_6636

Here's all the components before going through the reflow oven:

IMG_6639

Next solder the Through-Hole components:

IMG_6646

  • Stacking GPIO header J1 (mounted on the bottom of the PCB)
  • JST 2.0 connectors JP1 - JP6, JP10 - JP15

Here's how the board looks finished:

IMG_6648

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