EEVblog #782 - The Dangers Of Reflow Soldering - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: August 20, 2015, 11:35:06 am
content: Dave shows why reflow soldering in a DIY oven can be tricky business for connectors and other parts, particularly ones designed only for through-hole soldering.Reflowing an existing board (and even new boards) can be fraught with danger.Phoenix Contact Connectors for SMT Production Through Hole Reflow:https://www.phoenixcontact.com/local_content_pdf/pdf_eng/52004352_EN_DE_LR.pdfLead Free Solder Paste Datasheet:http://www.aimsolder.com/sites/default/files/nc254_sac305_solder_paste_rev_17_0.pdfHirose connector datasheet:http://www.hirose.co.jp/cataloge_hp/en_DF13_20130411.pdf

author: Godzil
author_rank: Frequent Contributor
timestamp: August 20, 2015, 11:58:26 am
content: OopsBut I'm happy to see that even a not so young player as you can make some mistake like this, I feel as a "young player" much confortable with my own mistakes

author: TheAmmoniacal
author_rank: Unknown
timestamp: August 20, 2015, 12:06:46 pm
content: No 2-row 90 degree pin headers in your lab? Looks like standard pitch.

author: McBryce
author_rank: Super Contributor
timestamp: August 20, 2015, 12:15:18 pm
content: Reporting serious under-use of your Fail button.McBryce.

author: Fungus
author_rank: Super Contributor
timestamp: August 20, 2015, 12:15:36 pm
content: Even a "cheap-ass DIY oven" could have an Arduino-controlled alarm system with a few temperature sensors dotted around.When the alarm goes off you could open the door and point a fan at the board. It'll cool down real fast.

author: Jfcarrer
author_rank: Newbie
timestamp: August 20, 2015, 12:27:14 pm
content: Still better than what this guy did to his graphics card:

author: dmg
author_rank: Regular Contributor
timestamp: August 20, 2015, 12:38:35 pm
content: Quote from: Jfcarrer on August 20, 2015, 12:27:14 pmWhat the hell happened in there? Did he try to reflow the board in a glass melting oven or something? Source?

author: TheAmmoniacal
author_rank: Unknown
timestamp: August 20, 2015, 12:46:40 pm
content: Quote from: Jfcarrer on August 20, 2015, 12:27:14 pmThat guy either left it in for a month or used a kiln!

author: McBryce
author_rank: Super Contributor
timestamp: August 20, 2015, 01:04:28 pm
content: Looks like he left the heatsink attached?McBryce.

author: amyk
author_rank: Super Contributor
timestamp: August 20, 2015, 01:15:40 pm
content: Probably left it in the oven and forgot about it until the smell got noticed...I think it's a regular oven (not on cleaning cycle), as anything higher and the plastic would've been burned instead of just melted.Incidentally there's this recent thread about the same problem, although there the peak was much higher and faster, and burnt the plastic instead of melting it first:https://www.eevblog.com/forum/reviews/reflow-oven-burning-part/msg732691/

author: AF6LJ
author_rank: Unknown
timestamp: August 20, 2015, 01:39:23 pm
content: Quote from: dmg on August 20, 2015, 12:38:35 pmIt looks like it was hit with blow torch.

author: Ampere
author_rank: Regular Contributor
timestamp: August 20, 2015, 02:50:17 pm
content: Quote from: Jfcarrer on August 20, 2015, 12:27:14 pmIt looks more like it survived being chucked into his fireplace.I've never done any reflow soldering, but I think that I'll start off doing it by hand. I don't trust my toaster oven to not bake my PCBs to a crisp like his did.

author: Protonus
author_rank: Newbie
timestamp: August 20, 2015, 03:12:15 pm
content: Please don't give up on this TV! I mentioned in the other thread that I'm working on one with a near identical issue (also a Samsung from '09, this one is a much thicker, 55", without the low profile cuts in the board, etc). I found bad Sam Young filter caps on the supply board and until I watched your videos was sure that those were the problem (replacements arrive today... I'll know tonight!). If it's not those caps I'm not sure where I'll go next for the repair ugh!

author: zapta
author_rank: Super Contributor
timestamp: August 20, 2015, 03:15:40 pm
content: Dave, in retrospect, what would you do? Protect the connectors somehow? Localized hot air? Remove the connectors?

author: 6581
author_rank: Unknown
timestamp: August 20, 2015, 03:58:48 pm
content: I love the smell of molten plastic in the morning.

author: AF6LJ
author_rank: Unknown
timestamp: August 20, 2015, 04:10:44 pm
content: Quote from: zapta on August 20, 2015, 03:15:40 pmYou would desolder them and set them aside.The only thing you can do if you are going to use a reflow oven.

author: Rasz
author_rank: Super Contributor
timestamp: August 20, 2015, 04:11:00 pm
content: Quote from: zapta on August 20, 2015, 03:15:40 pmnot reflow whole board in the first place, there is only few chips that would need it (bga)whacking whole thing into the oven is a quick shot from the hip hack, good for troubleshooting, but not exactly by the book

author: SundayProgrammer
author_rank: Contributor
timestamp: August 20, 2015, 07:36:36 pm
content: Quote from: Jfcarrer on August 20, 2015, 12:27:14 pmIt must be burned on purpose...Axel.

author: AF6LJ
author_rank: Unknown
timestamp: August 20, 2015, 08:48:00 pm
content: Quote from: SundayProgrammer on August 20, 2015, 07:36:36 pmI have a couple I would like to have done that to....Oh wait....There was this cheapo frequency counter I picked up for 5 bucks at the swap meet, I couldn't get it to work reliably so one day in a fit of anger I took a blow torch to it. Never seen so many crispy 74XX series logic chips...

author: Tothwolf
author_rank: Regular Contributor
timestamp: August 21, 2015, 10:27:09 am
content: If you go to look for replacement connectors, check JAE and Foxconn as well. Both Hirose and JAE are very popular in Japanese electronics. Those connectors look somewhat like JAE to me, but hard to tell without really digging into the datasheets.

author: amyk
author_rank: Super Contributor
timestamp: August 21, 2015, 01:01:11 pm
content: Quote from: Tothwolf on August 21, 2015, 10:27:09 amJST too, but those look generic enough that I think there'll be matches from several manufacturers.

author: EEVblog
author_rank: Unknown
timestamp: August 21, 2015, 01:35:51 pm
content: Quote from: zapta on August 20, 2015, 03:15:40 pmIf I wasn't so gung-ho I would have used a pre-heater on the bottom and then selective hot air on top of suspect chips.

author: coppice
author_rank: Super Contributor
timestamp: August 21, 2015, 04:37:02 pm
content: Quote from: zapta on August 20, 2015, 03:15:40 pmPut an ice pack on the connectors, of course. :-)

author: senso
author_rank: Frequent Contributor
timestamp: August 21, 2015, 09:07:08 pm
content: Quote from: Rasz on August 20, 2015, 04:11:00 pmGrab one of this babies:http://www.kurtzersa.com/electronics-production-equipment/rework-inspection-systems/rework-systems/produkt-details/ir-pl-650-1.htmlNever melted a single connector be it laptops, desktop, cellphone, any pcb, well just one time when I tried to crank it to 300ºC just to see how the pcb would react having true 300ºC in it.

author: f4eru
author_rank: Super Contributor
timestamp: August 22, 2015, 09:54:10 pm
content: Hello,Also beware of through hole caps !I once re-reflowed a board like you did to attempt a repair, and the (small) through hole caps i should have removed exploded, peppering the floor of the oven with smd parts and cap remains....

author: VK3DRB
author_rank: Super Contributor
timestamp: August 23, 2015, 08:43:17 am
content: I don't agree with the "cool it down as quick as possible after reaching the peak temperature". Temperature differentials can cause stresses in components, leading to component failure. Controlled cooling is the best approach. Hence one of the reasons for the preheating. Using toasters that are unmodified can create hot spots and cold spots. Having a more controlled oven environment reduced the chance of hotspots. Check this out...http://www.whizoo.com/. He installs plenty of insulation and reflective material the oven to avoid hotspots. He also uses a controlled door opener for cooling using a servo motor. From what I heard, the ControLeo's work very well.Whoever laid out those boards in the video scores 9/10. A great job. Component designators clear, and the smart engineer used triangles for pin 1 designators rather than those fly vomit round dots that are unfortunately so common. He has also labelled things like the i2c bus signal labels. Consistency is important - he did use a few round dots. Another issue is the large QFICs are better oriented 45 degrees to the direction of applying paste so there is no shadowing... statistically you generally get higher yields. Still, the boards are well laid out.Good video!