solution to "lift" TO-5 / TO-39 package - Page 1
Forum section: electronics / projects

author: roland
author_rank: Newbie
timestamp: January 21, 2016, 07:44:29 pm
content: Hi all,I'm designing a product that uses a PIR sensor (IR movement detection), it's a Panasonic EKMB.... type.The sensor comes int classic TO-5 (round metal can, 3 legs) package. The plastic lens comes with the part and fits directly on the TO-5 case. The TO-5 is soldered to the PCB by hand.Picture of the sensor here:http://media.digikey.com/Photos/Panasonic%20Elect%20Works%20Photos/EKMC1601111.JPGThe sensor needs to portrude from the housing, and because I have to use a standard housing and the location of the PCB is already fixed, the sensor needs to be a little higher (16.5mm) than it would naturally be when just soldered down.So I'm looking for a solution to "lift" the sensor. I considered using a TO-5 socket, but those socket seems to be extremely expensive (in $'s even in quantities), and I would need several of them to reach my 16.5mm. Or maybe some standard female pin headers, but it's not so easy to find the right parts for the pitch required by TO-5 (effectively 5.08mm / 0.2").Yes, of course I could design a little dauger board, solder the TO-5 on this and run a cable or some spacer pin headers to the main boards. But that's a fair amount of work just to do this job. And the cable solution wouldn't do the job since the sensor isn't mechanically fixed with this.Does anyone have an ingenious idea/solution for this kind of challenge?Greetings,Roland

author: krapht
author_rank: Contributor
timestamp: January 21, 2016, 07:49:40 pm
content: Can you not use 3 individual female pin headers?

author: roland
author_rank: Newbie
timestamp: January 21, 2016, 07:54:12 pm
content: That's a possible solution, however it seems more than difficult to find standard female pin headers of this size (roughly 16,5mm), and an additional challenge is to find single ones. Normal pin headers can't really be separated, precision pin headers can, but for production quantities >> 10 that also doesn't seem so reasonable.

author: nfmax
author_rank: Super Contributor
timestamp: January 21, 2016, 07:57:31 pm
content: Five of these maybe?http://uk.rs-online.com/web/p/connector-spacers/0402175/

author: roland
author_rank: Newbie
timestamp: January 21, 2016, 08:01:35 pm
content: Thanks - a good link, especially the price seems reasonable. That definitely addresses the "mechanical stability" issue. However, the leads of that sensor are not long enough for the job. Panasonic just gives me 4mm leads...

author: edpalmer42
author_rank: Super Contributor
timestamp: January 21, 2016, 08:15:53 pm
content: Your options are limited with only 4mm of lead to play with.I don't know where you'd find one, but a TO-5 socket with wirewrap pins would do the job. Just space it off the board the appropriate distance to get the sensor where you want it.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 21, 2016, 08:36:14 pm
content: Plastic TO5 spacers are quite common. Available from Mouser, Farnell etc. They are usually used to lift a TO5 to enhance airflow when a "star" heatsink is attached. Search for "Transistor pad"

author: dom0
author_rank: Super Contributor
timestamp: January 21, 2016, 09:17:16 pm
content: Two separate rows of normal three pin precision female headers?

author: rsee
author_rank: Contributor
timestamp: January 22, 2016, 02:50:06 am
content: If you were to try the cable option, could use secure the sensor to the housing with RTV, epoxy, or even hot glue?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 22, 2016, 05:13:09 am
content: It's that 16.5 mm height requirement that is the problem, considering the 4mm leads on the Panasonic part.I just looked in my stash at a few brand-new PIR sensors in TO-5. Even they don't have leads long enough to fit the height requirement. These have about 14 mm leads.Sounds like a daughter-board with spacer, and either cable or long pins on the DB, is going to be the only solution, unless you can find a different PIR sensor with extra-long factory leads.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 22, 2016, 08:54:00 am
content: A daughter board also need spacers with this offset. Extra connectors for mounting a daughter board makes material and assembling cost substantial higher. Imho wire-wrap pins hold in place by transistor pads, looks simplest.

author: Pack34
author_rank: Frequent Contributor
timestamp: January 22, 2016, 04:46:55 pm
content: If it has to be that high, you could always use a secondary small circuit board and then run wires down to where you need it. Then mount the second board to the main one using standoffs.

author: nfmax
author_rank: Super Contributor
timestamp: January 22, 2016, 05:52:06 pm
content: How about a vertical daughter board? (I mean perpendicular to the main board). R/A board connector at the bottom and R/A dual-row socket header at the top?

author: roland
author_rank: Newbie
timestamp: January 22, 2016, 06:35:38 pm
content: Thanks guys for all the suggestions. I'll try two things: use wire-wrap pin headers (types with >20mm are available) and then plug the sensor on top. In addition, use TO-5 spacers. Or as an alternative, use TO-5 spacers and just solder additional wire to the leads of the sensor to make them longer.

author: Ian.M
author_rank: Super Contributor
timestamp: January 22, 2016, 07:26:44 pm
content: I think Emmanuel's idea of a vertical daughterboard soldered straight into a slot in the main PCB, with the sensor edge mounted has promise. I think a 1.5mm or 1.6mm double sided board should fit snugly between the sensor pins. The main PCB end would have shoulders to set the height and the sensor end would be notched to center the sensor so its legs line up with the pads. If the daughter boards are on a carrier strip with a V groove across the main PCB end, you could use an assembly jig to locate a batch of sensors along the board ends for hand soldering of two pins, then flip the strip over, solder the remaining pin and snap them off as required at the main PCB assembly station. The main PCB pad layout would be such that an incorrectly inserted sensor PCB couldn't be soldered.