# Doesn't building a circuit “Manhattan-style” introduce lot of parasitic capacitance?

I watch a lot of circuit building videos on Youtube and I can see that the "Manhattan" style of circuit building (placing small islands of copper clad board on a larger piece which acts as the ground plane, and soldering components across the "islands") is quite popular.

I can see that this method is used even in high frequency circuits such as small transmitters. But won't this introduce a lot of stray capacitance, as an "island" of copper clad board on top of the ground piece is essentially a parallel plate capacitor?

Let's say one island is $$\ 0.005m\ *\ 0.005m = 2.5 * 10^{-5}m \$$. I have some of such board and I measured its thickness as approximately $$\1.3mm\ =0.0013m.\$$ Therefore the capacitance between an island and the ground plane would be $$\C=\epsilon_{0}\frac{A}{d} = 8.854*10^{-12}*\frac{2.5*10^{-5}}{0.0013m}=1.7*10^{-13}F.\$$

At radio frequencies such as 100Mhz, the impedance would be $$\\frac{1}{2\pi f C} =\frac{1}{2\pi*100*10^{6}*1.7*10^{-13}}=9400 \Omega\$$.

This isn't a short circuit, but it isn't very large either. So why do we use this method of construction? What advantages do we get using it that makes it worth having these $$\9400\Omega\$$ extra impedances to ground? Wouldn't it be better to build on stripboards for example, that don't have that same problem?

• It would be pretty nifty if you could edit this to include a photo of what you're talking about. Just grab an appropriate one and reference it well. I considered doing it myself, but it will better reflect what you're talking about if you do it yourself. – Scott Seidman Aug 15 at 13:36
• Even worse, $C=\epsilon_{0}k\frac{A}{d}$ where k is about 4-5 for FR4 – glen_geek Aug 15 at 13:54

The two main advantages of using the Manhattan style of assembly are

1) A solid ground plane underneath everything
2) A secure construction
3) You're not constrained by the geometry of stripboard