Review: Pi-EzConnect Terminal Block Breakout HAT

I bought one of these recently:Pi EzConnect Adafruit product 2711

I’ve done a moderate bit of raspberry Pi prototyping on and off. The choice has usually been either a piece of stipboard and some cables or an incidental prototyping area on an expansion card of some sort (like the excellent motor hat). This time, I decided to go pro and buy a ready made breakout board.

This one:

2711-06

It’s OK, and there’s a good chance I’ll use it in the final project, but it has a few flaws.

If you look in the photo above, the GPIO holes are doubled up. I can see why they did this but it makes the prototyping area painfully small. In addition, the labels for the terminals and holes is on the inner side. They could have put them on the otherwise outside and had an extra two rows of holes, giving 10 rows instead of 8.

Another flaw is that the painfully small prototyping area is not matrix board, it’s stripboard style. Now normally I’d say this is down to personal taste. I quite like stripboard, personally. However out of the main options of stripboard, tri-pad and matrix, it’s the least compact because of all the track cuts needed. Matrix board is arguably the most faffy and annoying style, however it’s by far the most dense and in a space limited situation like this, density is I think the most important thing.

So essentially, they could have nearly doubled the useful prototyping area of the board, and used a higher density proto typing style.

The other thing I really didn’t like was the terminal style.

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That leaf spring inside the terminal greatly reduces the usable area, to the point where I couldn’t fit in a piece of tinned speaker wire. I have a 100m reel of the stuff that I use for many miscellaneous wiring odd jobs., and I had to older on a thin piece of single core wire. In fact I have very little multicore cable narrow enough to fit in those holes.

It’s a shame because there are better styles that have a moving gate inside which has a lot more capacity for the same pitch, like this one:

r7176634-01

All the usual suspects have similar types (Phoenix Contact, TE Connectivity, RS Pro, plus a bunch of vendors on Ali Express).

It seems like a selection of small things but over all they add up to a breakout board that’s not as good as it could be. If you have small wires and little soldering needs then it will work perfectly, but it could be a good deal more flexible.

Overall, 3/5

T962 Reflow oven review.

My local hackspace has an excellent T962A reflow oven. I’ve used it a number of times with perfect results (when I didn’t foul up—Kids, don’t use old paste!), and it gets excellent reviews online.

It’s a pain to cart everything back and forth and put everything away before going home, so I figured I’d try out the smaller T962 oven. It doesn’t get such uniformly positive reviews, but it’s substantially cheaper and substantially smaller (space at home is fairly limited).

The main disadvantages are a lower maximum temperature (280C—which is more than enough for unleaded solder), a smaller area, and if the mixed reviews are to be believed, rather more uneven heat distribution especially out towards the edges. The latter isn’t a problem for me because I’m planning on doing small prototypes, so I’m unlikely to get anywhere near filling the tray.

Opening it up it essentially looks like a smaller version of the T962A:

T962 reflow oven

Unlike some of cheap electronics manufacturing goods it feels very solid, the one exception being the tray which is a little rickety going in and out. A small price to pay for a reflow oven I can actually afford. The manual of the T926A took some effort to read (the translation is a little wonky in places), but this machine has an identical user interface which is nice, so I was up and running fast.

For my first test solder I decided to go for the trickiest thing I could think of. I have a tub of unleaded paste of unknown composition (I only know it’s unleaded since the T962A at the hackspace failed to reflow it on a leaded profile) which has been opened for a year. I “reconditioned” the paste by mixing in a bit of rosin flux gel. I smeared some over an old, spare board with a toothpick and placed a few random 0603s and set it going.

The first run smells bad in the generic “new parts getting very hot” sort of way. Similar to the smell I got after using an electric hob for the first time after cleaning it. Make sure you run it first in a more than usually well ventilated area.

Reflowing looks like this:

reflow

It’s quite hard to see well, but the resistors have nice smooth shiny blobs of solder over them, and the solder where it hit the various pads has reflowed well. You can’t see in the photo, but the silkscreen has come out slightly discoloured due to the high temperature (the discolouration you can see is due to the flux). Unleaded boards done in the T692A also had a discoloured silkscreen but with slightly less discolouration. The discolouration isn’t completely uniform which indicates that the heat distribution isn’t completely uniform.

Still, it seems to work, and leaded solder (what I use for prototyping) is very forgiving compared to unleaded.

Conclusion

Seems to work on small boards, but the temperature is a bit uneven. I’ll update when I have some full boards to reflow.

Edit:

I did the boards that I bought the oven for.

The results are essentially perfect. Nice even heating (over the small area), no toombstoning, good shiny solder blobs, good separation on the DFN with a 0.5mm lead pitch. And the boards work too!

I’d recommend this oven for anyone with small to moderate amounts of reflow to do. If you’re going to be regularly filling it up to the edges (especially using unleaded paste), then the 962A is almost certainly a better bet.