Analog Devices - text on the effect of humidity on voltage references - Page 1
Forum section: electronics / general

author: daqq
author_rank: Super Contributor
timestamp: September 12, 2019, 07:11:39 am
content: Interesting read:https://www.analog.com/en/analog-dialogue/articles/does-my-voltage-reference-design-hold-water.html?ADICID=EMAL_WW_P1274_SUB-NL-PN_547&9039

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2019, 08:02:59 am
content: The plastic packages molding consists of 75% fused silica (imagine silicagel balls) and up to 5% of water (the rest is epoxy and black pigment)..

author: Andreas
author_rank: Super Contributor
timestamp: September 12, 2019, 05:18:21 pm
content: Hello,you should not intermixFused silica = Silica glass: CAS No. 60676-86-0 = SiO2 = QuartzandSlilica GEL: CAS No. 63231-67-4 = SiO3H2Semiconductors use Silica glass:https://www.analog.com/media/en/package-pcb-resources/material-declaration/pdip/PDIP_300_8lds(n-8).pdfhttp://quality.linear-web.com/rohs.php?part=LT1027CCN8-5%23PBFinteresting is that LT uses different plastic than AD.Perhaps that is the reason why I measured ~0.5ppm/%rH at a LT1027 and Lars measured ~0.1-0.2 ppm/%rH at a AD587 reference.with best regardsAndreas

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2019, 05:47:57 pm
content: SiO2 + H2O = SiO3H2Jokes aside..Quotefromhere.From the same source - baking times in days - to get a certain percentage of the moisture off the package.How to seal them up afterwards, that is the question..

author: Gyro
author_rank: Super Contributor
timestamp: September 13, 2019, 08:58:19 am
content: Quote from: daqq on September 12, 2019, 07:11:39 amA useful demonstration (confirmation) from the AD that board coatings are useless for mitigating the effect of humidity changes on their epoxy packaged references.Meantime, let's phase out hermetic packages and make it someone else's problem.

author: SilverSolder
author_rank: Super Contributor
timestamp: September 13, 2019, 12:51:32 pm
content: Quote from: Gyro on September 13, 2019, 08:58:19 amInteresting that even ceramic packages are not completely immune.

author: Andreas
author_rank: Super Contributor
timestamp: September 13, 2019, 06:06:13 pm
content: Quote from: SilverSolder on September 13, 2019, 12:51:32 pmEspecially the SMD ceramic packages are influenced largely by the epoxy PCB.with best regardsAndreas

author: iMo
author_rank: Super Contributor
timestamp: September 13, 2019, 06:16:49 pm
content: Thus you cut a hole in the pcb (or dead bug style) and do bond the ceramic package with thin wires, I guess..What MAX/ADI/LT references in the ceramic packages would you recommend?

author: Andreas
author_rank: Super Contributor
timestamp: September 13, 2019, 06:53:29 pm
content: Quote from: imo on September 13, 2019, 06:16:49 pmAD586LQ, AD587JQ (selected)

author: eplpwr
author_rank: Regular Contributor
timestamp: September 21, 2019, 02:40:05 pm
content: Regarding the article: Where did they find ADR4525 in a ceramic package? I can find a new "C" grade @ DigiKey et al, but no version in ceramic SO-8 ...

author: iMo
author_rank: Super Contributor
timestamp: September 21, 2019, 04:30:16 pm
content: The chip manufacturers usually use ceramic packages during development and testing of the devices (as they may connect some hidden contacts on the chip easier for testing purposes).

author: .rk.
author_rank: Newbie
timestamp: October 23, 2019, 10:53:35 pm
content: The product page shows a pre-release "D" grade. It says 0-70°C for the temp range.https://www.analog.com/en/products/adr4550.html#product-samplebuy

author: jbb
author_rank: Super Contributor
timestamp: October 26, 2019, 02:06:49 am
content: Analog Devices / Linear Tech are producing parts in an SMT ceramic package called “LS8” now. Could be useful. Some are indeed available ex Digikey.If you don’t need the absolute best tempco, there are some nice low noise options too.