Talk:Surface-mount technology

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[edit] Pictures

It would be very helpful, at least until all the minor articles are made (QFN, TSSOP, etc.), if links to picture of the different packages were available. This would add to the list. --Matejhowell 21:09, 16 February 2006 (UTC)

I'm glad to see that the photo i posted of an SMD prototyping board was deleted. I admire the genius that solders wires to the IC and puts the picture out there for the world to see. Ninevoltz 13:10, 2 September 2007 (UTC)

[edit] Updates to "Assembly Techniques"

  • Solder paste is actually composed of flux and tiny balls of solder, all of uniform size. (This would make a neat picture.)
  • Brass stencils are also frequently used (although falling out of favor).
  • In my experience, adhesive dots are rarely used for double-sided assembly (only when having to place heavy components on both sides of the board). Adhesive dots are required to allow SMT components to be flow soldered onto the solder side of a through-hole board.
  • Minor, but the pre-heat zone also allows volatile components of the solder paste to evaporate, to avoid boiling during soldering.
  • Vapour phase reflow is rapidly falling back into favor due to RoHS (lead free) soldering.
  • From what I know, only a small percentage of boards are washed, perhaps someone can back this up with some published stats. Most processes rely on "no clean" fluxes which do not need cleaning.

I agree with everything else. --Adx 13:27, 31 March 2006 (UTC)

I agree about the seldom-washing of PCB's. We use an EMC Stencil Cleaner and only wash boards that have misplaced parts or which had errors in solder screen printing. If nothing goes wrong we do not wash boards at all.

At times though when something has been wave-soldered we will wash it. But again, not every time. --lsjzl 14:58, 17 May 2006 (EST)

[edit] Splitting SMD technology from SMD packages?

Seems the surface mount technology page is becomeing more a list of used packages rather than a presentation of the technology as such. Maybe it's suitable to split it into two seperate sections? —Preceding unsigned comment added by Electron9 (talk • contribs) 23:29, 26 June 2006

[edit] Adding a few words about automated optical inspection

I think it would be wise to mention that visual inspection can be done either by human, or by automated inspection machines. —Preceding unsigned comment added by 192.118.27.253 (talk • contribs) 11:56, 2 January 2007

[edit] Any reference why is MQFP listed in Non-packaged devices?

I don't understand why MQFP is considered to be non-packaged. Could anyone provide a reference? From the article: "Non-packaged devices (although surface mount, these devices require specific process for assembly)" --Alsh 07:23, 31 January 2007 (UTC)

Ask CyrilB, who "tidied the list" on 7 June 2006. Most likely an editing oversight. —QuicksilverT @ 08:15, 31 January 2007 (UTC)
Ooooops! My fault! This is corrected now CyrilB 20:39, 31 January 2007 (UTC)

[edit] Adhesive for securing parts pre-soldering

In the History section, the article states "...parts on the bottom or "second" side of the board are temporarily secured with a dot of adhesive..." Is this always the case, as the word "are" implies? I've never witnessed the process, but I could envision iterations of some soldering processes where the PCB is simply flipped over (either manually or automated) after the top side is soldered, thus eliminating the need for an adhesive step for each component. I would suggest replacing "are" with "can be" just to clear up any confusion. Or does this not make any sense at all? TheJalAbides 18:35, 16 March 2007 (UTC)

[edit] Dirt Cheap Reflow Method

I have reflowed the solder in a cellular phone with a cracked lose solder joint on a power connecter by using a graphite rod (also known as a mechanical pencil "lead") and 6V power supply. The metal to be resoldered is connected to ground, and a point about 1/6th up the graphite rod is connected to +6 with an alligator clip. The remaining 5/6ths of length will serve as insulator: hold the alligator clip that holds the graphite rod for positioning, but press down on the graphite rod from the far end for down-force (facilitating heat transfer) on the component. Turn the power on. When you can start to feel that the rod is getting warm (at the tip), its time to stop. Turn the power off, but continue to hold the rod down until it again feels cool, allowing the solder at the bottom to harden and set.

  • The graphite rod heats up smoking hot very quickly, but the graphite won't steal the solder away from the circuit-board like a regular soldering iron will; it has no affinity whatsoever for the stuff.
  • The graphite rod seem doesn't radiate heat nearly as quickly as a soldering iron either, nearby components are left unmelted and undamaged provided they are not actually touched with the hot graphite.
  • No insanely high warming index flurocarbons, no pressurized burning hot gasses, no toxic (lead) or expensive (gold) heavy metals in the solder. Requires only the very basic stuff you probably already have anyways if you do any electronics work at all, and works great if you have a steady hand! If nobody else came up with this first, just call it the Kennerly Process... I'll post a YouTube video soon enough. (Cripes, were we really using vaporised FCs when we could have been using hot pencil lead?!?!?)Zaphraud 20:40, 9 October 2007 (UTC)
I'm not sure about the method above... but I guess it depends on the type of graphite rod you use. The ones in pencils are different to other industrial types. Who came up with the above method? Can you be more detailed? Zaphraud, is that your method or are you criticizing someone else's method? --78.86.159.199 (talk) 04:48, 24 January 2008 (UTC)

[edit] Manufacturers

This section is so incomplete that it seems to me to be not only not useful, but actually harmful. On the other hand, if it WERE to be made complete, it would basically list everyone who makes discrete semiconductor devices, also not terribly helpful. I am therefore removing it. Wegsjac (talk) 18:58, 18 January 2008 (UTC)

[edit] Contradiction

In the advantages section it is mentioned that : "Simpler automated assembly" Where as in the disadvantages section it is mentioned that: "The manufacturing processes for SMT are much more sophisticated than through-hole boards, raising the initial cost and time of setting up for production"

Assembly and Manufacturing are almost the same thing. The "simpler automated assembly" line needs to be elaborated, e.g. By adding why its simpler, e.g. there are fewer steps involved, instead of just saying its simpler. Whats simpler? And for the latter, the sentence needs to highlight that its not the assembly/manufacturing process that is more sophisticated, but the process involved in setting up manufacturing that is more sophisticated, e.g. "Setting up the manufacturing processes for SMT is more sophisticated than through hole boards raising the setting up time and initial costs".

If anyone disagree's, please state why, and if you do agree, then lets agree upon on a replacement sentence. Thanks --78.86.159.199 (talk) 00:44, 24 January 2008 (UTC)

[edit] Rework

The rework procedure for revisions/faulty products is quiet uncommon. The cost of making a PCB is very small, it is highly unlikely a manufacturer would rework a PCB based on a recall or repair since the disassembly, shipping and other passive costs would outweigh the costs of making the part from new. Also, when many of the components are replaced with new ones, resulting in the production of a totally new PCB much more feasible than a rework --78.86.159.199 (talk) 00:51, 24 January 2008 (UTC)

[edit] Disadvantages

Two missed out disadvantages for SMT: 1. is the lack of strength for soldered components. Through hole components hold themselves better to the board than SMD components. 2. There are limitations to the types of components that can be made in SMD packages. Most capacitors, mosfets etc. need to be made in through hole casings as well as connectors etc.

It is also worth mentioning that manufacturers would need both SMT processing machines as well as through hole processing machines since most circuit boards require a component combination of both. One reading this article would assume SMT is an equilavent alternative to through hole processing, but this article needs to emphasize that regardless of SMT, through hole processing is still needed and used in all PCB manufacturing plants.--78.86.159.199 (talk) 01:03, 24 January 2008 (UTC)

[edit] Please move the packages to a 'packages' or 'footprint' page.

They're almost impossible to find here on the "surface-mount technology" page. Who would think to look for "surface mount technology" when trying to find SOT or SO8? In any case, a pointer from the 'footprint' disambiguation page would be useful. —Preceding unsigned comment added by 150.101.166.15 (talk) 06:49, 15 May 2008 (UTC)