Manhattan on the Strips

written on Wednesday, February 17, 2016

I've always liked prototyping with a solderless breadboard, as it is fast to build, easy to modify and poke around with probes - until I tried to build a prototype of a very simple project (on a breadboard), but it refused to function correctly. I soldered it - and it bloody well worked! After some investigation it turned out, that:

  • contacts of a solderless breadboard are not tight

  • as an interface between component lead and a board clip is not tight, there is some electrical resistance between them, and - to my experience - this resistance is not negligible at all. Once I was able to measure the voltage drop with my multimeter just across the jumper connected to a solderless breadboard!

To mitigate the issue, I've come up with an old idea of placing components on the copper side of a stripboard - like in the very inspiring Manhattan building technique - and to my mind, the proposed method has the following advantages:

  • no need to flip the board while soldering and measuring - less adventures with holding components in place and in addition, you see the components while measuring

  • less manual work, as there are already copper strips, which are partially interconnecting components - you still need to make jumper wires and you still need to occasionally remove copper using 3mm drill bit

  • using copper strips as access points for measurements

  • SMD 1205 components can be used, thus simplyfying the job even further; still, thru-hole componenst are the foundation of the method.

All other prototyping techniques, like Dead-Bug/Point-to-Point/Manhattan/Bird's Nest etc. - are very good and sometimes they are the only choice for amature RF, but they are also relatively slow to build and an absolute overkill for a simple circuits, which you would want to assemble as quickly as possible without compromising the reliability.

Frequency-wise, this method has the same limitations as normal stripboard method.

I was not able to find any equivalent technique in the Internel, so I'll post my own pictures and recommendations - hopefully, they will be useful for a reader.

Photos of the technique

two-boards

proto-1-ov

proto-2-ov

proto-3-ov

Layout and preparations

  • when making a layout, try to have at least one hole (2.54mm) of free space around the component - this small precaution makes the whole process of future modifications much simpler, as you can add and remove components without a hassle Remember, each component:

    • must be accessible at any time

    • can be desoldered at any time

    Your layout should be very easy and comfortable to modify and accessible to take measurements.

  • Try to stay as close to the schematics as possible, even if it takes more space - this helps a lot to recall the details after a pause, and make it less tricky to debug

  • do not spend time in cutting tracks between the holes - use 3mm drill bit to remove the copper around the hole.

  • clean the stripboard thouroughly - it can be a pain in the neck to solder contaminaded copper stripboard

  • verify the layout: try to place all components on a stripboard and see, is it enough space

Try to make the process of building prototype, modifiying it and debuging as easy as possible for you - less frustration, more pleasure!

Soldering

  • Use kapton tape to hold SMD components in place and flux copper and tinned surface of the component to facilitate the process. I have good results with a chinese variant of kapton tape.

  • use appropriate bit for your soldering iron, capable of storing and delivering plenty of heat - copper strips are perfect heat-"suckers". My favorites are Antex XS 25 (25 watt) and Ersa Multityp 260 (16 watt), both with chisel (screwdriver) tips: 2.3 mm and 2.6 mm respectively. These tips are chunky and perfectly do their jobs in heating copper strips and component leads.

    ersa-antex-tips-1

    ersa-antex-tips-2

  • Tip from Ersa is a bit wider then a tip from Antex, but this fact doesn't really prevent anybody from soldering 1205 SMD resistors and capacitors accurately.

  • I do not recomment 18-watt Antex for this job - its tip just doesn't store enough heat to deal with the copper strips

  • avoid making component leads too short or too long

  • For a right-handed person, place and solder components from left to right (reverse for the left-handed)

  • Do not spend a lot of time to make the components upright before soldering: the moment the first lead of a component is soldered (as-is), apply flux, melt the solder again, make in verticale with a finger of the second hand and then let the solder cool down without taking off the finger from the component. The rest is trivial:)

    proto-2-side

    proto-1-side

  • do not throw out desoldered components - if they are fine, you should be able to re-use them later!

SMD placement

  • Variants of mounting SMD: vertically between two strips of copper or horizontally over the drilled hole.

proto-1-smd

proto-2-smd

Conclusion

I hope, this technique will be useful for a reader - with some training, the prototypes will be relatively fast to build, easy to modify and debug. That's it - happy prototyping!

Categories: electronics and soldering

blog comments powered by Disqus