Metal fusion bonding – Process – Plural joints
Patent
1993-07-27
1995-01-17
Ramsey, Kenneth J.
Metal fusion bonding
Process
Plural joints
2282341, B23K 100
Patent
active
053819454
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the soldering of parts, such as printed circuit boards or sets of components in the field of electronics, or metals in the field of mechanical manufacture. Processes of that kind result in a solid connection of the soldered parts by means of a solder, wherein said solder has to be melted beforehand.
It is known from DE-A-39 15 040 that the parts to be soldered should be preheated by spraying them with a liquid before the actual vapor-phase soldering is carried out. It is known from DE-A-10 81 088 that after the soldering process, the soldered joint should be submitted to a thermal aftertreatment by means of a vapor jet. The actual soldering process, however, is usually a flow solder method or a common reflow solder method like infrared soldering, hot-air soldering or vapor-phase soldering.
Known soldering processes are the flow solder method wherein already liquid solder is applied to the soldering area, and several reflow soldering methods wherein the solder is applied on the parts beforehand and is melted during the process in order to produce the soldered joint. Examples of such reflow soldering methods are infrared soldering, wherein the melting of the solder is carried out by means of infrared radiation; hot bar soldering, wherein the heat transfer is carried out through contact; hot-air soldering, wherein the heat transfer is carried out by convection; and vapor-phase soldering, wherein the heat transfer is carried out by condensation of the vapor in the area to be soldered,
When using these known soldering processes, a thermal overloading of the parts to be soldered is hard to prevent. An optimized process should be aimed at keeping the temperatures of the parts to be soldered as low as possible, i.e. just above the melting point of the solder. During the known soldering processes, there is generally a temperature difference of at least 30.degree. C. between the temperature of the heat transfer medium and the melting point of the solder. This temperature difference is necessary to ensure a safe soldering process during the time interval needed for manufacture while keeping the heat transfer in mind. Also, the mentioned processes do not allow to exactly control the temperature or to carry out minor temperature adjustments during the heat transfer.
In another known process for the tinning of printed circuit boards, excess solder is removed by means of a hot liquid, e.g. oil, after the tinning process. Such a process is referred to as "Hot Oil Leveling". It involves the spraying of pressurized hot oil onto the printed circuit board. The oil causes the excess solder to melt, levels the soldered connection and removes the excess solder. Afterwards, the oil has to be cleaned off the printed circuit board. This method cannot be used for the soldering process itself.
The problem underlying this invention is to provide a process for the soldering of parts such as printed circuit boards or modules in the field of electronics, or metals in the field of mechanical manufacture, resulting in a small temperature load on the parts, a finely and variably adjustable heat transfer as well as a clean and cost-effective process.
This problem is solved by the features of the claims.
The solution of the invention is based on the concept that the temperature at the soldering area can, by means of a liquid at the desired temperature, be controlled in such a way that it is at or slightly above the melting point of the solder with the liquid also entering gaps and that by means of the favorable heat transfer properties of the liquid the heat is passed on quickly to the soldering area.
The advantages of the invention are the following: The temperature of the liquid can be precisely controlled--and, if desired, additional influence can be exerted by controlling the amount of liquid--, therefore any desired soldering profile can be predetermined; a very slight increase in temperature can be effected which ensures maximum protection of electronic components; due to an even spreading of the l
REFERENCES:
patent: 2986811 (1961-06-01), Rudd
patent: 3298588 (1967-01-01), Shomphe
patent: 3435801 (1969-04-01), Carini et al.
patent: 3724418 (1973-04-01), McLain
patent: 3825994 (1974-07-01), Coleman
patent: 4022371 (1977-05-01), Skarvinko et al.
patent: 4240453 (1980-12-01), Vial et al.
patent: 4315042 (1982-02-01), Spigarelli
patent: 4332342 (1982-06-01), van Der Put
patent: 4453916 (1984-06-01), Osipov et al.
patent: 4489508 (1984-12-01), Carlson et al.
patent: 4589926 (1986-05-01), Holmstrand
patent: 4809443 (1989-03-01), Mishina et al.
patent: 4830263 (1989-05-01), Dexheimer
patent: 4874124 (1989-10-01), Johns et al.
patent: 4927068 (1990-05-01), Naka et al.
Weichloten in der Elektronik by R. J. Klein Wassink, pp. 189, 258-260, 351-352, 363. (1986).
M. Bucher, Reflow-Lotverfahren in Vergleich, Elektronik, 7, pp. 108-110, 112, 113, Mar. 31, 1988.
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