DRV8833 with cooling pad

[real-bombinho]

I was looking at the DRV8833 IC (not a board), it is a TSSOP16.

I could not find a Fritzing part for the DRV8833 hence I grabbed the first TSSOP16 part I could find and had a go at modifying the PCB part.

DRV8833 PDF

This is what I came up with so far:

My issue is that only a part of the copper is supposed to be exposed and I have no idea how to do this, also the cooling pad should be both sides, can this be realised?

Maybe like this?

<g id="copper1" stroke-linecap="round" stroke-width="0">
  <rect id="connector0pad" x=".114" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="1"/>
  <rect id="connector1pad" x=".764" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="2"/>
  <rect id="connector2pad" x="1.41" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="3"/>
  <rect id="connector3pad" x="2.06" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="4"/>
  <rect id="connector4pad" x="2.71" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="5"/>
  <rect id="connector5pad" x="3.36" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="6"/>
  <rect id="connector6pad" x="4.01" y="5.8" width=".45" height="1.5" fill="#F7BD13" connectorname="7"/>
  <rect id="connector7pad" x="4.66" y="5.8" width=".4" height="1.5" fill="#F7BD13" connectorname="8"/>
  <rect id="connector8pad" x="4.66" width=".45" height="1.5" fill="#F7BD13" connectorname="9"/>
  <rect id="connector9pad" x="4.01" width=".45" height="1.5" fill="#F7BD13" connectorname="10"/>
  <rect id="connector10pad" x="3.36" width=".45" height="1.5" fill="#F7BD13" connectorname="11"/>
  <rect id="connector11pad" x="2.71" width=".45" height="1.5" fill="#F7BD13" connectorname="12"/>
  <rect id="connector12pad" x="2.06" width=".45" height="1.5" fill="#F7BD13" connectorname="13"/>
  <rect id="connector13pad" x="1.41" width=".45" height="1.5" fill="#F7BD13" connectorname="14"/>
  <rect id="connector14pad" x=".764" width=".45" height="1.5" fill="#F7BD13" connectorname="15"/>
  <rect id="connector15pad" x=".114" width=".45" height="1.5" fill="#F7BD13" connectorname="16"/>
  <rect id="connectorHeatPadT" x=".114" y="1.9" width="5" height="3.4" fill="#f7bd13" connectorname="17"/>
  <g id="copper0"> 
    <rect id="connectorHeatPadB" x=".114" y="1.9" width="5" height="3.4" fill="#f7bd13" connectorname="17"/>
  </g>
 </g>

I had a look how the ATMEGA1284 realises the vias and tried to copy the concept. But I could not see a bottom pad.

Footprint
TSSOP16 with cooling pad

Type
I did not read this
Breakout board, sub assembly, plug in module (A)
Antenna (AE)
Battery (BT)
Capacitor (C)
Diode (D)
Display (DS)
Fuse (F)
Hardware , mounting screws, etc. (H)
Jack, fixed part of a connector pair, header (J)
Relay (K)
Inductor, Coil, Ferrite bead (L)
Loudspeaker, Buzzer (LS)
Motor (M)
Microphone (MK)
Plug, moveable part of a connector pair (P)
Transistor (Q)
Resistor (R)
Thermistor (RT)
Varistor (RV)
Switch (S)
Transformer (T)
Integrated Circuit (IC)
Crystal, Oscillator (Y)
Zener diode (Z)
Other (please specifiy)

[real-bombinho]

@KjellM Has Fritzing the ability to have solder mask covered copper in parts?

[RAPTOR7762]

sorry i’m no expert, but can you attatch a screenshot? Maybe can undrstand better

[real-bombinho]

Hi RAPTOR7762,

my apologies I am not entirely sure which screen I am supposed to provide.

This is the best picture I could find on the quick:

The solder area is relatively small but as per picture above the manufacturer recommendation is to make a large heat pad with vias but cover it with solder mask except of the area that can be soldered.

[RAPTOR7762]

Ok @real-bombinho I’ll spend some time digging my brains and the web

[real-bombinho]

Thank you, I have found heat pads with vias (e.g. the above mentioned ATMEGA1284) but nothing indicating if Fritzing parts can have a solder mask layer.

Also the ATMEGA1284 puzzled me as it seems to have the vias but no bottom pad.

[real-bombinho]

I just modified the schematic file to match

[KjellM]

Ideally Fritzing would allow a to directly protect copper, but currently this is not supported.

One possible workaround would be to manually remove the it from the gerber file.
This is manual and error prone, it will be easy to forget this step when perparing the sketch for the Fab.

The maskTop is a negative of the mask, so the rectangle (an outline of it) will be an object in the file.

Load in gerbv, select the mask layer:

Select the mask negative we want to remove, click it:

Right click for the menu:

Remove it:

For better visualization, you can invert the mask.
End result:

I think adding support for soldermask0 and soldermask1 in parts should not be too difficult, so I have added it to our backlog.

[real-bombinho]

Hi @KjellM,

thank you for your answer

IMHO the desired result would have been more like

Yes, I think, adding solder mask to parts may become more and more important.

Parts are getting smaller and solder mask as protection as well as cooling pads have become a frequent occurrence for me now (and that is me mostly working with devices long out of support).

[real-bombinho]

I have been experimenting and so far I get Fritzing to actually display the heat pad front and bottom + vias from the part. Unfortunately uploading at Aisler does remove the pad from the underside and the vias are not recognised.

Currently adding vias manually and connecting them to ground is the only workaround I have found so far.

Due to the tight spacing this is not a fun process.