BlueBoard#01 is...

A 100mm by 100mm board that's for prototyping and one-off projects that use SMT and through-hole components. 

BlueBoard #01
An earlier prototype

Features

Footprint Compatibility

SMT parts come in a huge variety of package shapes and sizes, however many of them share pin pitches. With care and attention, it’s possible to have a single footprint that can be used to mount many different types of packages, and this is the approach BlueBoard#01 takes.

The following table shows the dimensions of each footprint on the board, along with common compatible package names and examples of compatible parts.

Remember to always check the package drawing in the datasheet to verify that the part will fit. In particular, check:

Footprint

Common package names

Example compatible parts

1.27mm 28 pad

8SOIC

8SO

14-SOIC

24SOIC

28-SOIC

PIC12F509T-I/SN MCU

PIC16F616T-I/SL MCU

AD674BBRZ 12-bit ADC

NCV7708BDWR2G Hex Half-bridge Driver

CD4514BM96 4bit latch, 4:16 decoder

0.65 / 0.635mm 28 pad

8-MSOP

14-TSSOP

28SSOP

PIC12F509T-I/MS MCU

PIC16F616T-I/ST MCU

AS1130 LED Dot Matrix Driver

LTC1450CG#PBF 12-bit DAC

0.5mm 10 pad

8-SSOP

8-VSSOP

10-MSOP

10-uMax

74LVCH2T45DC,125 Voltage Level Translator

AD5161BRMZ10-RL7 SPI Digital Pot

MAX4327EUB+T 5MHz RRO Op Amp

SOT23-8

SOT23-8

MAX6846KARD3+T Battery Monitor

TPL0501-100DCNR Digital Pot

SOT23-6

SOT23

SOT-23-3

SOT23-5

SOT23-6

TO-236-3

SC-59

5-TSOP

TSOP6

SC-74

SOT457

+ many more

DMN65D8L-7 N-CH Mosfet

BZX84-A12,215 Zener Diode

MCP6001 Op Amp

MCP1640 Boost Regulator TLV271SN2T1G Op Amp 3MHZ RRO

SC70-6

SC70-5

SC70-6

SC88

SOT363

MCP6001 Op Amp

NTJD5121NT1G Dual N-Ch Mosfet

24-VQFN

24-VQFN 4x4 0.5mm Pitch

24-VFQFN

See section below.

SPU410LR5H-QB-7

-

See section below.

The 24-VQFN Footprint

The 24-VQFN footprint supports a wide range of 8, 16 and 32 bit microcontrollers (Digikey search) as well as audio amplifiers, DACs, ADCs, digital switches, LED drivers, half bridges and more.

This footprint is for a 4mm x 4mm package, with leads at 0.5mm pitch and an exposed pad. The exposed pad is not thermally connected to a large plane, but that should not present a problem for most uses. The package dimensions are taken from the “24-Lead Very Thin Plastic Quad Flat, No Lead Package (RLB) - 4x4 mm Body [VQFN]Atmel Legacy Global Package Code ZHA” document.

Always double check the datasheet for dimensions, in particular the package size (4mm x 4mm) and pin pitch (0.5mm).

I have had a lot of success using the ATTiny3217, a low power but highly capable MCU, and am looking forward to experimenting with the ATSAM11L which has a Cortex M-23 core, 16K of RAM and lots of fun peripherals. I'm going to keep the TAS2505 I2S class-D amplifier in mind, too.

This footprint is designed to be soldered with a hot air gun, but it is possible to get a soldering iron onto the pads.

The Microphone Footprint

This board has a footprint the Knowles SPU0410LR5H-QB-7 MEMS Analog Microphone.

MEMS microphones are performant and, at 0.76USD/single, cheap. However they are difficult to experiment with unless you already have a PCB with the correct footprint.

The microphone mounts on this footprint. The V+, Ground and Out terminals are routed to the marked terminal strips.

The microphone port is at the bottom of the package - it listens through a hole in the PCB.

The other side of BlueBoard#01 - shown in the diagram below - has the V+, ground and output terminal strips marked with a “V+”, “G” and “O” respectively. The microphone port comes out next to the “T” in SOT.

Tips on the SPU0410LR5-QB-7

Until you get to know it, this component can be a little finicky to work with.

Hand soldering: because the pads are underneath the microphone, this component isn't usually hand solderable. However, the BlueBoard#01 footprint features extended V+, Gnd and Output pads shaped to allow a chisel edge soldering iron to heat all 3 pads simultaneously. 

  1. Pre-tin the microphone pads with a little solder
  2. Pre-tin the whole length of the exposed PCB pads with a little solder
  3. Position the microphone on the PCB in the outline (double check you have it the right way around, so the the microphone port is over the hole.
  4. Heat the pads by holding your soldering iron on all three pads simultaneously. This works best with a 2.5mm+ width chisel tip. The solder will melt and flow. Push the microphone down gently with tweezers to ensure all three pads are connected. When all the solder is flowing, you should be able to (very) gently push the microphone to the side and have it snap back into position due to surface tension.
  5. Remove the soldering iron.
  6. Flip the board over and check that you can see through hole in the PCB, into the microphone port.

Tips: 

Square Pad, Staggered Hole Prototyping

The majority of BlueBoard#01 is given over to square pads. Here are some things to keep in mind when using them.

LEDs soldered across terminal strips1. Solder two-terminal surface mount components to the squares.
1. Solder two-terminal surface mount components to the squares.

Through hole and SMT components, peacefully co-existing

2. Through hole components can go … through the holes.

3. A row of two or more 0.1” header pins will be held securely by the staggered holes. This is great for adding test leads or programming MCUs.

4. Similarly, through hole DIP packages will sit in the staggered holes. Depending on the stiffness of the pins, you may not need to solder.

I would solder this DIP

5. There are three, two-wide bus strips on the board, and also terminal strips running across the board in a pattern familiar to anyone who has used a solderless breadboard. This greatly reduces the need for additional wiring.