08-07-2011, 08:29 PM
SURFACE CONTAMINATES
1. Solder solvent action and the corresponding wetting cannot occur unless the base metal is free of all oils, greases, dirt and any chemical reactions. All metals and metal alloys, when exposed to air at room temperatures, are constantly under going chemical reactions. These reactions are primarily oxidations, the combining of an element with oxygen. Small amounts of nitrides, sulfides, and carbides are also forming depending on the ambient conditions. ( This is the main reason for our tracks getting dirty)
2. Oxides of aluminum, magnesium and stainless steel are very hard and act as a shield for the metal, protecting it from further chemical attack. Copper, silver and lead oxides fortunately are easier to remove, therefore soldering to these metals can be facilitated by the use of mild fluxes.
Flux Core Solder
1. One restrictive feature about soft solder fluxes is that they are generally unsuited to sustained high temperature applications due to a fundamental thermal instability. For instance, no soldering flux possesses the stability or resistance to thermal decomposition to remain continuously active at the temperature of a soldering iron, which normally runs from about 600 degrees to 800 degrees F.
2. Organic and Resin type fluxes, in which the naturally organic solvents are singularly prone to volatilize at low temperatures. However, in addition to loss of solvent and subsequent decrease in ionic behaviour, the organic and resin fluxes themselves are highly subject to thermal decomposition, carbonization, or volatilization at temperatures not far greater than the boiling point of any solvent that may be employed.
"The Golden Rule of Soldering"
1. Briefly this rule stipulates that the cored solder strand must be applied at the exact junction between the flat surface of the adequately heated soldering iron and the metal being soldered, ( except when soldering pre-tinned conductors and component leads ) in order that solder and flux may be simultaneously liberated at the exact point where solder adhesion is desired. The soldering flux, unlike molten solder, will not flow down the side of a hot soldering iron.
2. In general, as heating proceeds, an insulating film of oxide rapidly forms over the surface of both metals which retards the flow of thermal energy, and it is at this point that the application of flux becomes important. As the strand of solder melts, the released flux removes the oxide films so that the intervening space is immediately filled with a conductive column of solder to the unit being soldered.
3. In addition, there must be a thermally conductive column of molten solder, between the two hot surfaces in order to secure successful and efficient soldering.
Flux
1. Flux can be a solid, paste or putty, a liquid or even a gaseous material, which when heated is capable of providing or accelerating wetting of a material by solder.
Purpose of flux
1. It cleans, removes and excludes oxides and other impurities from the joint being soldered.
2. Prevents re-oxidation. (The molten flux flowing on the joint excludes air from the joint.)
3. Aids in the wetting action.
Classes of Flux
1. Corrosive --------- Inorganic salts and acids
2. Non-Corrosive -- Natural rosins only, which sometimes has mild additives
Types of Flux
1. Type R ----------- Rosin
2. Type RMA ----- Rosin mildly activated
3. Type RA -------- Rosin highly activated
Forms of Flux
symbol form
1. S Solid (meaning solid metal with no flux)
2. L Liquid
3. P Paste or Plastics
4. D Powder or Pellets
Flux Percentage
Solder which has flux manufactured into it has a percentage rating. The percentage of the flux that is manufactured into the solder is based on weight. Meaning that "X" amount of solder has "X" amount of flux in it. The flux percentage symbols are: 1, 2, 3, 4 and 6. The percentage amounts are as follows:
percentage symbol flux percentage
1 --------------------- 0.8 thru 1.5
2 --------------------- 1.6 ------ 2.6
3 --------------------- 2.7 ------ 3.9
4 --------------------- 4.0 ------ 5.0
6 --------------------- 6.0 ------ 7.0
Properties of Rosin Flux
1. Melts at 260 degrees F. and remains active in molten state to 600 degrees F.
2. Will decompose and char at 545 degrees F.
3. Active constituent of rosin is abietic acid.
4. Abietic Acid:
A. Inert in solid state
B. Active when molten
C. Becomes inert (inactive) when it cools
5. Activators added are organic chlorides:
A. Primarily, Amine Hydrochloride
B. At soldering temperatures, hydrogen chloride is released to do chemical cleaning
(at disassociation temperatures)
C. It will recombine upon cooling leaving non-corrosive residues.
Forms of Solder:
Solder comes in several different types of forms and these forms are noted by a single
letter.
1. - B -- Bar
2. - I -- Ingot
3. - P -- Powder
4. - R -- Ribbon
5. - W - Wire
6. - S -- Special ( includes pellets and pre-forms )
Now that we have covered several different forms of solder and flux, lets take a look at a spool of solder to see just what type of solder it is and weather or not it has a flux core center. When reading the label on the side of a spool of solder, I see the following code: Sn60 W R 2
From what we learned above, we know that Sn60 is showing us that the solder is made up of
60% tin and 40% lead. The "W" is showing that the solder form is of wire type. The "R" is showing that the wire solder has a rosin center core and the "2" is showing that the rosin flux percentage is "1.6 - 2.6".
If we see: Sn60 W S, we know that the solder is 60% tin and is of wire form and it is solid wire with out a rosin core center.
If we see: Sn60-W-R-P2, we know that the solder is 60% tin and is of wire form and it has a rosin core center and that the rosin is a paste or putty with a percentage rating of 2.
This is the end of the topic. Thanks to Randy Cline for his work and to all who provided the questions and answers.
Check out the companion piece to this thread, "The Solder Shop Q&A", HERE
1. Solder solvent action and the corresponding wetting cannot occur unless the base metal is free of all oils, greases, dirt and any chemical reactions. All metals and metal alloys, when exposed to air at room temperatures, are constantly under going chemical reactions. These reactions are primarily oxidations, the combining of an element with oxygen. Small amounts of nitrides, sulfides, and carbides are also forming depending on the ambient conditions. ( This is the main reason for our tracks getting dirty)
2. Oxides of aluminum, magnesium and stainless steel are very hard and act as a shield for the metal, protecting it from further chemical attack. Copper, silver and lead oxides fortunately are easier to remove, therefore soldering to these metals can be facilitated by the use of mild fluxes.
Flux Core Solder
1. One restrictive feature about soft solder fluxes is that they are generally unsuited to sustained high temperature applications due to a fundamental thermal instability. For instance, no soldering flux possesses the stability or resistance to thermal decomposition to remain continuously active at the temperature of a soldering iron, which normally runs from about 600 degrees to 800 degrees F.
2. Organic and Resin type fluxes, in which the naturally organic solvents are singularly prone to volatilize at low temperatures. However, in addition to loss of solvent and subsequent decrease in ionic behaviour, the organic and resin fluxes themselves are highly subject to thermal decomposition, carbonization, or volatilization at temperatures not far greater than the boiling point of any solvent that may be employed.
"The Golden Rule of Soldering"
1. Briefly this rule stipulates that the cored solder strand must be applied at the exact junction between the flat surface of the adequately heated soldering iron and the metal being soldered, ( except when soldering pre-tinned conductors and component leads ) in order that solder and flux may be simultaneously liberated at the exact point where solder adhesion is desired. The soldering flux, unlike molten solder, will not flow down the side of a hot soldering iron.
2. In general, as heating proceeds, an insulating film of oxide rapidly forms over the surface of both metals which retards the flow of thermal energy, and it is at this point that the application of flux becomes important. As the strand of solder melts, the released flux removes the oxide films so that the intervening space is immediately filled with a conductive column of solder to the unit being soldered.
3. In addition, there must be a thermally conductive column of molten solder, between the two hot surfaces in order to secure successful and efficient soldering.
Flux
1. Flux can be a solid, paste or putty, a liquid or even a gaseous material, which when heated is capable of providing or accelerating wetting of a material by solder.
Purpose of flux
1. It cleans, removes and excludes oxides and other impurities from the joint being soldered.
2. Prevents re-oxidation. (The molten flux flowing on the joint excludes air from the joint.)
3. Aids in the wetting action.
Classes of Flux
1. Corrosive --------- Inorganic salts and acids
2. Non-Corrosive -- Natural rosins only, which sometimes has mild additives
Types of Flux
1. Type R ----------- Rosin
2. Type RMA ----- Rosin mildly activated
3. Type RA -------- Rosin highly activated
Forms of Flux
symbol form
1. S Solid (meaning solid metal with no flux)
2. L Liquid
3. P Paste or Plastics
4. D Powder or Pellets
Flux Percentage
Solder which has flux manufactured into it has a percentage rating. The percentage of the flux that is manufactured into the solder is based on weight. Meaning that "X" amount of solder has "X" amount of flux in it. The flux percentage symbols are: 1, 2, 3, 4 and 6. The percentage amounts are as follows:
percentage symbol flux percentage
1 --------------------- 0.8 thru 1.5
2 --------------------- 1.6 ------ 2.6
3 --------------------- 2.7 ------ 3.9
4 --------------------- 4.0 ------ 5.0
6 --------------------- 6.0 ------ 7.0
Properties of Rosin Flux
1. Melts at 260 degrees F. and remains active in molten state to 600 degrees F.
2. Will decompose and char at 545 degrees F.
3. Active constituent of rosin is abietic acid.
4. Abietic Acid:
A. Inert in solid state
B. Active when molten
C. Becomes inert (inactive) when it cools
5. Activators added are organic chlorides:
A. Primarily, Amine Hydrochloride
B. At soldering temperatures, hydrogen chloride is released to do chemical cleaning
(at disassociation temperatures)
C. It will recombine upon cooling leaving non-corrosive residues.
Forms of Solder:
Solder comes in several different types of forms and these forms are noted by a single
letter.
1. - B -- Bar
2. - I -- Ingot
3. - P -- Powder
4. - R -- Ribbon
5. - W - Wire
6. - S -- Special ( includes pellets and pre-forms )
Now that we have covered several different forms of solder and flux, lets take a look at a spool of solder to see just what type of solder it is and weather or not it has a flux core center. When reading the label on the side of a spool of solder, I see the following code: Sn60 W R 2
From what we learned above, we know that Sn60 is showing us that the solder is made up of
60% tin and 40% lead. The "W" is showing that the solder form is of wire type. The "R" is showing that the wire solder has a rosin center core and the "2" is showing that the rosin flux percentage is "1.6 - 2.6".
If we see: Sn60 W S, we know that the solder is 60% tin and is of wire form and it is solid wire with out a rosin core center.
If we see: Sn60-W-R-P2, we know that the solder is 60% tin and is of wire form and it has a rosin core center and that the rosin is a paste or putty with a percentage rating of 2.
This is the end of the topic. Thanks to Randy Cline for his work and to all who provided the questions and answers.
Check out the companion piece to this thread, "The Solder Shop Q&A", HERE