FAQ
- Questions on Industry Specification
- Questions on Alloy type
- Questions on Hand Soldering
- Questions on Process ( Wave )
Questions on Industry Specification
Q1. What is the difference between R, RMA and RA?
| Type R | - | stands for rosin. More specifically non-activated rosin. This is the mildest type of flux available. |
| Type RMA | - | stands for rosin, mildly activated. This is the most commonly used flux type by military contractors. It has some activity but it is still very mild. |
| Type RA | - | stands for rosin, activated. This is a active flux and more popular with consumer electronics. |
Q2. What is the comparison between the old flux type & the J-Standard?
See comparison table below:
| Old Code | J-STD-004 |
|---|---|
| R – Rosin Only | ROL0 |
| RMA – Rosin Mildly Activated | ROL1 |
| RA – Rosin Activated | ROL1 ROM1 |
| WSF – Water Soluble | ORH1 |
Q3. Can Electroloy conforms to QQ-S-571 Federal Specification?
Yes Electroloy’s solder products can conform to this specification. But the industries now prefer to use IPC J-STD.
Q4. What is IPC J-STD?
Since 1984 a committee of military and commercial 'experts' have been working to update the Mil specs. At the same time, IPC in conjunction with the American National Standards Institute (ANSI) were also working to create up to date flux, solder and solder paste standards. Last June the government got out of the specification writing business and turned it all over to the IPC.
The result is the following J Standards:
The result is the following J Standards:
| J-STD-001 | - | Requirements for Soldered Electrical and Electronic Assemblies
(Suggested Replacement for MIL-STD-2000) |
| J-STD-002 | - | Solderability Tests for Component Leads, Terminations, Lugs, Terminals and Wires |
| J-STD-003 | - | Solderability Tests for Printed Boards |
| J-STD-004 | - | Requirements for Soldering Fluxes (Suggested Replacement for MIL-F-14256) |
| J-STD-005 | - | Requirements for Soldering Pastes |
| J-STD-006 | - | Requirements for Electronic Grade Alloys & Non-Fluxed Solid Solders for Electronic Soldering Application (Suggested Replacement for QQ-S-571) |
Questions on Alloy type
Q1. In what sectors is lead in solder exempted?
In high temperature solder where lead is more than 80%. Lead is also permitted in sectors dealing with network infrastructure equipment for switching, signalling, transmission as well as telecommunications.
Most of this exemption runs out by 2010, but possible extension may be necessary for some sectors as there is still no replacement. While others had already converted to lead free before the run out date.
Most of this exemption runs out by 2010, but possible extension may be necessary for some sectors as there is still no replacement. While others had already converted to lead free before the run out date.
Q2. What is the permitted lead content in a lead free solder?
Current industrial standard specification for lead impurity is 500ppm, although RoHS limit is set at 0.1% or 1000ppm. Therefore care must be exercise to avoid lead contamination especially during wave soldering.
Q3. What is the standard lead free alloy for almost all lead free assembly operations?
The SAC family of alloys have become the most commonly used alloy for reflow process because of a lower melting temperature, while the low Ag version is becoming popular in the wave process because of lower alloy cost.
The SnCu based solder, particularly those containing certain additives is popular for wave and HASL processes because better joint finishing and lower alloy cost, although operating temperature is higher compared to SAC alloy.
The SnCu based solder, particularly those containing certain additives is popular for wave and HASL processes because better joint finishing and lower alloy cost, although operating temperature is higher compared to SAC alloy.
Q4. What are the patent issue for using lead free solder?
There are more than 150 patent worldwide, therefore the selection of lead free alloy must be done carefully so that proper licence fees are paid using these patented alloys. Some alloys do not need patent because of long history of use especially binary alloys, for example Sn/Ag, SnCu, SnBi etc.
The most common is
1) The SAC305 ( Sn/Ag/Cu ) by Iowa State University ( ISURF) with USA patent no : 5,527,628.
2) The SCN ( Sn/Cu/Ni ) by Nihon Superior Japan
Electroloy is license to manufacture & sell these patented solder alloys and the licenses pass through to Electroloy’s customers to use these alloys.
The most common is
1) The SAC305 ( Sn/Ag/Cu ) by Iowa State University ( ISURF) with USA patent no : 5,527,628.
2) The SCN ( Sn/Cu/Ni ) by Nihon Superior Japan
Electroloy is license to manufacture & sell these patented solder alloys and the licenses pass through to Electroloy’s customers to use these alloys.
Q5. What are some low temperature lead free alloys?
Low temperature alloys are those considered as having melting temperature lower than the Sn/Ag/Cu alloys or typically the SAC family. These are basically tin alloy with addition of bismuth, indium or zinc. Example Sn42/Bi58 melts at 138°C, Sn48/In52 melts at 118°C and Sn91/Zn9 melts at 199°C. These alloys can have its advantages as well as the disadvantages.
Q6. What are the high temperature lead free solder?
Currently there is no good alternatives other than the high lead solder. However there is some possibility like Sn95/Sb5 melts at 235-240°C, Sn95/Al5 melts at 382°C. These alternatives are not really high temperature lead free solder that comes with some solderability issues.
Questions on Hand Soldering
Q1. Will there be a reliability issue on the flux residue left after hand soldering?
Our no clean flux residues are non-corrosive and conductive & are generally safe. If better surface appearance is preferred, then cleaning can be performed.
For our water soluble flux, the residue is generally more active & thus cleaning after soldering is necessary. To maintain a shining joint is best to wash off within a few hours, otherwise the joints will be dull.
For our water soluble flux, the residue is generally more active & thus cleaning after soldering is necessary. To maintain a shining joint is best to wash off within a few hours, otherwise the joints will be dull.
Q2. At what tip temperature do you recommend for hand soldering?
This depends on the alloy & flux selection. For SAC alloy, tip temperature can be set from 360°C to 380°C. For Sn/Bi alloy, the tip temperature can be set at about 200°C.
Q3. Can I use a soldering iron for Sn/Pb for lead free hand soldering?
Generally you can still use it for lead free soldering, but the rate of soldering must be slower as the recovery rate of the iron is not design for lead free. Lead free alloys works on a higher temperature, thus a faster recovery rate of the iron is important for better soldering & good productivity.
Q4. How can I avoid having too much solder with hand soldering?
Excess solder can be caused by a few factors; the most common is operator skill or error, followed by incorrect wire diameter size for the job and thirdly insufficient flux or no flux. So ensure the above are corrected to minimize excess solder problem.
Q5. Why is there burned flux residue after hand soldering?
The problem arises when the temperature of the iron is set too high together with inadequate iron maintenance. Burned flux residue can contaminate joints causing voids & joint reliability. Work within the right temperature & ensure the tip is cleaned before soldering.
Q6. Why is there soldering spike or icicles after hand soldering?
Solder pike is reported to be one of the common problems. They are the result of several factors.
1) Poor soldering technique can cause spike by allowing the joints to partially solidify before the tip is removed.
2) Insufficient heating can also cause spike, this can be partially contributed by poor iron temperature control.
3) Less flux content also produces solder spike because solder oxidizes when melted and insufficient flux action
results in an oxide outer layer of the solder that increases the probability of a solder spike.
So proper training is essential to make a good solder joint coupled with proper equipment and right selection of solder wire with the correct flux content.
1) Poor soldering technique can cause spike by allowing the joints to partially solidify before the tip is removed.
2) Insufficient heating can also cause spike, this can be partially contributed by poor iron temperature control.
3) Less flux content also produces solder spike because solder oxidizes when melted and insufficient flux action
results in an oxide outer layer of the solder that increases the probability of a solder spike.
So proper training is essential to make a good solder joint coupled with proper equipment and right selection of solder wire with the correct flux content.
Questions on Process ( Wave )
Q1. Does most lead free alloy erode stainless steel faster than other material in the solder bath?
All high tin alloys will erode stainless steel. There is no specific data to determine the erosion rate of stainless steel from one lead free alloy to the other, thus there is a need to increase the preventive maintenance checks to prevent leakage.
Q2. Are special flux chemistry needed for lead free soldering process?
Generally, lead free alloy can be used with most flux chemistry, although consideration must be taken on the alloy composition & melting point. Flux chemistry must be able to withstand the higher process temperature & slower process speed.
Q3. Are the reliability issue for cross contamination of two different lead free alloys?
The only worry for cross contamination that will affect the solder joint life during the wave process is lead to SAC or other lead free alloys. Any lead contamination above 0.5% is detrimental to the solder joints.
Whereas the mixture of SAC & Sn/Cu + Ni were found to be compatible with one another when mixed by using a different touch up wire alloy as the one used in the wave process. Thus a two alloy system can be successfully used for mixed technology boards without compromising reliability.
Whereas the mixture of SAC & Sn/Cu + Ni were found to be compatible with one another when mixed by using a different touch up wire alloy as the one used in the wave process. Thus a two alloy system can be successfully used for mixed technology boards without compromising reliability.
Q4. Will there be more dross generated for a lead free process?
Generally there will be more dross generated with lead free alloy due to the higher processing temperature. However this can be overcome by anti-oxidant additives incorporated into the alloy system. Good machine setting can help minimize the drossing effect.
Q5. How can I maintain the copper, iron and lead concentration in the solder pot.
As explained on question 3, lead concentration is the most critical & difficult to remove unless a partial or full pot change is done. Whereas increase of iron concentration is an indication of pot erosion is taking place. Increased in copper concentration can be resolved by using alloy without copper for top up to maintain the balance of the copper concentration in the pot.
To know when such action is to be taken, a periodical analysis is necessary for the solder. Electroloy can provide such analysis upon request.
To know when such action is to be taken, a periodical analysis is necessary for the solder. Electroloy can provide such analysis upon request.
