# Edge-mount SMA connector for ~100mil board thickness

I have a footprint on a ~100mil thick PCB for an SMA edge connector:

I find millions of SMA edge connectors for 62mil board thickness and I found a single one for 32mil (https://www.adafruit.com/product/1864).

However, I found none for ~100mil thickness.

Do they exist? And if not, is there any hack to still install an SMA connector reliably? (Frequency range is up to 3 GHz, RL as good as possible but not critical; price secondary).

It is worth to mention that the PCB is already fabricated with the footprint above. That means I cannot change footprints, holes, thickness etc.

• Watch out with some of the answers below recommending though hole connectors. You can easily find a VSWR of 2:1 at 3 GHz, if you're not careful. Make an array of test boards with short lines with connectors at each end, and vary the size of the centre conductor pads on both layers, and the size of the hole in the ground plane. With care you can achieve 1.2:1. If you want better, or just to have it more predictable, use an edge connector. – tomnexus Mar 21 '18 at 19:38
• No they don't exist because thicker substrates generally result in worse performance >>1GHz from dielectric loss. You will need to do as @tomnexus suggested above with a variety of sample connectors. – Tony Stewart Sunnyskyguy EE75 Mar 21 '18 at 19:47
• Did you get any answers or have more specs? – Tony Stewart Sunnyskyguy EE75 Mar 21 '18 at 21:56
• One very important point is your dielectric thickness and proximity to bottom layer ground plane affects Zo, VSWR, RL of your pad geometry significantly. – Tony Stewart Sunnyskyguy EE75 Mar 21 '18 at 22:14
• Also your effective Dk value reduces with rising f and is affected by laminate thickness somewhat as per IPC-2141A – Tony Stewart Sunnyskyguy EE75 Mar 21 '18 at 22:33

There are a couple of styles of SMA edge-launch connector that are very flexible about board thickness.

This type was I believe originated by Southwest Microwave, but is now available from a couple other vendors:

This type originated with Rosenberger:

But either of these types has lots of parts so it will be very high priced for a 3 GHz application.

Why not just use the old standard through-hole right-angle type?

The pins are typically a bit over 100 mils, so you shouldn't have trouble soldering them. For best signal integrity, mount this type on the opposite side of the board from where your signals are routed.

There are some options to accommodate your pre-existing footprint. Like this one from Amphenol,

Or several similar. They offer edge-mount connectors for 0.093" and 0.11" board thick, but they are not just like a "fork", and need two holes to mount.

However, your footprint doesn't look very "impedance matching" friendly, so doing hacks will definitely cause some serious impedance mismatch.

Also, "Adafruit" is not the best place to shop for RF connectors. Try Mouser, Digi-key, or more specialized places.

In addition tot he answers given by The Photon, Rosenberger also have these:

But these are expensive. Really expensive.

Thanks to The Photon < I posted the wrong connector, but you are in luck. this one works as an edge insert to thick boards 0-18GHz $6(1) 116mil depth Best bet for 3GHz for cost and high performance if it can be made to suit application. Maximum VSWR is 1.20 (~21dB) at 11GHz Molex £1.37(1) Farnell Molex 0733910060$3 (1) 18GHz

When you find an RF connector with no VSWR or Return Loss specifications, be very concerned.

Consider machine and plating tolerances and the precision of the feed pin , how its soldered and any variations. These all significantly affect Return loss at 1GHz and much more at 10GHz etc...

Then decide if 10 dB RL is adequate for a cheap connector.

You ought to expect this in cheap mass-produced RF connectors without quality controls. Would rather pay extra for 30dB .. You can't afford 40dB or even need it because the geometric tolerances are < 100ppm and dielectric tolerances for d constant, also very tight.

Since you asked about 100 mil boards, I assume rigidity is important to you.

In this case consider adding rigid substrate or other stiffener mechanics.

From my experience, SMD connectors are just bad news mechanically for any type with forces applied to the cable and jack.

But I understand if you have a height restriction or packaging problem. There are alternatives. yours on left, on right Amphenol p.n. 901-10511-3

$2.50 left ,$13 right

Edge connectors take a lot of abuse and SMA connectors MUST be careful torqued by a calibration tool for optimal performance.

$25 (1) 02K249-40ML5 Rosenberger$105 (1)

My experience came from setting up Iridium Satphone LNA testset for mobile radio chips with Anritsu VNA calibrated to 0.1dB accuracy and 0.01dB resolution and working with Motorola, until they decided to decommission 1st system from lack of sales.

for kicks 110GHz rated >\$1k