Can someone help with me with a board for small surface mount sensor?

varnon

Hi all,

Any chance someone with a reflow oven can help me out with a few boards? We can work out a payment of course. This should be a simple job for someone with the right tools so it might be an easy way to make a few bucks. Unfortunately I have not be able to recruit any help from the engineering department at my university so I am hoping maybe one of you can help.

I have been using some AMS/TAOS TSL2561 light sensor breakout boards. They were pretty well, but I would really love to upgrade to the TSL2583, a drop-in replacement with better control options that AMS/TAOS rates as 30 times more sensitive than the TSL2561. The pinout and circuit requirements for the two sensors are identical. The breakout board designs offered by adafruit and sparkfun would work perfectly. Unfortunately, I lack the tools to work with such a small surface mount part. The larger surface mount parts I can handle. This sensor is particularly small.

I am hoping someone can put together a few breakout boards for me. This could be a simple as removing the sensor from a TSL2561 breakout board and installing the TSL2583 in its place. An underpopulated board can also be made from the open-source designs available at adafruit and sparkfun and then the TSL2583 and other components can be added.

You can see the datasheet for the TSL2583 here:
http://www.mouser.com/ProductDetail/ams/TSL2583FN/?qs=sGAEpiMZZMsznZCy4g9R5xlykJqgre6r

Open source breakout boards for the TSL2561 can be seen here:
https://www.sparkfun.com/products/12055
and here:
http://www.adafruit.com/products/439

Is anyone interested in this job? I would like 8 TSL2583 boards. I do understand that it is probably cheaper in the long run to put together a reflow oven and do it myself, but right now I am very short on time and not as short on funds.


Thanks.

homosapien

I think you are over-thinking the problem. If I was faced with this situation, I would:

1) Buy the Adafruit/Sparkfun boards.

2) Remove existing sensor with a soldering iron (maybe clip/cut legs off devices first to make it more of a 'wipe with iron' type procedure). You do not need a super tiny tip here, it might even be better to have a tip that will bridge the 3 pins on one side of the sensors.

3) Place new sensor in position, solder just by heating, there is usually enough solder left on the pads from the original part that you do not need to add any.

All you would need for this job is a soldering iron with a medium size tip, a cup of coffee and some good tunes.


my $.02

Nate

Heater.

Given that board design you want is open sourced I would proceed as follows:

1) Download the board design and send it off to a PCB house to get a few made. For example https://oshpark.com/ will get you a few of those boards for a few dollars.

2) Solder the chips down yourself. Surface mount may be tiny and look impossible but it can be done quite easily with patience.

Checkout some YouTube vids on how to do this. For example this by Dave L. Jones of the eevblog: https://www.youtube.com/watch?v=b9FC9fAlfQE

Don't forget the flux!

I would not get into buying a prebuilt board and ripping up the existing chip. That is going to be much harder.

varnon

Thanks for the thoughts. My concern is that it might not be possible to solder this chip without a reflow oven. It is a 6 pin device without leads. I think the term for this form is TMB? I don't think it can be done with a soldering iron. The chip also appears too small fragile to solder it with a hot air rework station (I tried). If it were something big like a surface mount resistor or a QFP chip I'm sure I could do it without too much of a problem.

RDL2004

I've seen videos of people soldering those flat-no lead packages by hand, but I'm pretty sure I'd never be able to do it.

tonyp12

>without a reflow oven
A dedicated toaster oven works, I prefer infra-toaster-ovens.

maybe this one: Panasonic NB-G110P (it looks like lab equipment to start with)
http://www.newegg.com/Product/Product.aspx?Item=N82E16896200436&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Toaster+Ovens-_-N82E16896200436&gclid=CjwKEAjw77OhBRCJ7Onfp_HNtwYSJACZqHAWkLNu-giGun_QgQ3_O73tYRLjPp_iXbpzTTrXvbiLhxoC1T7w_wcB

So order a stencil at oshstencil and solderpaste from digikey.

Leon

I've soldered chips like that with a soldering iron without any problems.

homosapien

I have to admit, I did not see that the sensor chips were of the legless variety when looking at the linked pictures of Adafruit/Sparkfun boards. However, I do not see that that really makes any difference.

Yes, it might be harder to remove the old sensor, but since you are not trying to save it, this would not be a deal breaker. In this case, I think a soldering iron tip that can contact all 3 pads on one side of the sensor at one time is necessary. Gently slip a knife blade just a tiny bit under the sensor, alternate heating the 3 pads on each side of the sensor until it comes loose. Each side heating is just to lift the sensor/slip the knife slightly farther under a tiny bit, if you go too fast you will end up ripping the pads off the board .

The advantage of using a pre-built board is that once the sensor is off, there is already solder on the pads and there is no real need for flux. Simply put the sensor in place, gently apply top pressure with something that will not damage the clear top (such as a wooden matchstick that you press down with your hand that is not holding the soldering iron) and alternately heat the 3 pads (they appear to stick out beyond the profile of the sensor, which is good) on each side of the sensor until it is laying flat and soldered, may take 3 or 4 (or more) alternations across to get it all settled in.

I have done this before (not the same device, but same mount technology) and it works fine. I always found hot air tended to blow everything away as well as heating up waaay more real estate than I wanted to.

Leon

Chip Quik works very well for removing surface-mount parts:

http://www.chipquik.com/store/

It's sold by D-K, Mouser and Farnell.

Tracy Allen

I'm partial to the Intersil ISL29033 or ISL76683 low light sensing. They too come in a 2mm ODFN package, like the TSL2583, but the pinout is different.

One reason I like the ISL parts is that the output is directly in units of lux, and it is pretty good under different lighting conditions. There are no additional calculations. Here is a comparison of the wavelength responses for the ISL29033 (green=lux, red=IR) and the TSL2583 (lux = linear combination of Ch0 wideband and Ch1 IR).