Solder Basics
Q1: Selecting a soldering iron.
A: It is important to select a soldering iron by considering the solder, components, and board which will be used.
In the case of components or boards with a large heat capacity, it is necessary to select a soldering iron which also has a large heat capacity. Furthermore, there are soldering irons with specially shaped tips designed for easy operation.
Q2: Metal used in solder.
A: Almost all solder contains tin. Also, a variety of other metals are used according to the task. These metals include led (Pb), copper (Cu), silver (Ag), bismuth (Bi), indium (In), nickel (Ni) and zinc (Zn).
Q3: The difference between brazing and soldering.
A: Brazing is one method of joining metal. This method uses a base material and an alloy with a lower melting point than the base material. The alloy is melted to join the metal.
Soldering is also a type of brazing and refers particularly to the joining of metal using solder. Normally, the term "solder" refers to alloys that melt at a temperature lower than 450 degrees Celsius.
At the Forefront of Solder
1. Cautions regarding RoHS
RoHS is an abbreviation that was made by taking the first letter from each of the words in the phrase "Restriction of Hazardous Substance".
Excluding a few exceptions, RoHS prohibits the sale of products which contain percentages of materials such as lead, mercury, and cadmium that exceed specified values. Sale of such products has been banned in EU member countries since July 1st of 2006.
Due to the regulations imposed on products, it is necessary to monitor all materials used in products.
2. Merits and demerits of solder coaters.
The merit of solder coaters is that it becomes easier to wet the board with solder. Since solder is affixed to the land in advance, melting with paste solder occurs easily.
The demerit is increased costs. However, we recommend the use of solder coaters when emphasizing reliability.
3. Difference between single reflow and double reflow.
The difference between single reflow and double reflow is the difference between a one-sided board and a two-sided board.
In the case of two-sided boards, printing, component mounting and reflow must be performed for each side. Therefore, it is necessary to perform reflow twice. Selection of components is important because side A, which underwent reflow first, will be heated a second time.
4. The mechanism of copper corrosion.
The term "copper corrosion" refers to when the copper of the land or lead wire dissolves (spreads) into the solder.
The speed at which the copper spreads is greatly influenced by the copper concentration (within the solder) and the temperature of the solder. If there is a high copper concentration within the melted solder, then the copper spreads at a slow speed. Prevention of copper corrosion is one of the reasons that copper is contained within SAC 305, a type of solder which is currently widely used.
5. Conditions for solder which is used in automobiles and other vehicles.
In the case of automobiles and other vehicles, malfunction due to solder defects is directly linked to the life and death of human beings.
For that reason, there is the condition that solder pass a large number of strict evaluations which are performed. Due to outdoor usage and the effect of vibration, it can be said that vehicles are the most severe operating environment for solder.