JPH04266999A - Detergent composition - Google Patents

Abstract

PURPOSE:To obtain a detergent composition, dryable in a short time and suitable for washing water-soluble fluxes used for especially soldering on-vehicle printed circuit boards by mixing a pentafluropropanol with water at a specific ratio. CONSTITUTION:A detergent composition is obtained by mixing (A) 85-90wt.% pentafluoropropanol with (B) 10-15wt.% water and used for washing water-soluble fluxes, etc., in which ethylene glycol, etc., are blocked with alkyl groups. The aforementioned composition is capable of providing a substitute for a chlorofluorocarbon R113(R) (1,1,2-trichloro-1,2,2-trifluoroethane) having <=45sec drying time and responding to washing with the existing solvent equipment.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a cleaning composition, and more specifically, a pentafluorinated propanol cleaning composition suitable for cleaning water-soluble flux used in soldering printed wiring boards. Regarding. In addition, below,
This pentafluorinated propanol is abbreviated as “5FP”.
Also written as

0002

2. Description of the Related Art Conventionally, when soldering printed wiring boards, a rosin-based flux is applied, and this flux is cleaned with a mixed solvent of Freon R113 (trade name) and ethanol. However, in recent years, it has been pointed out that fluorocarbons such as R113 may destroy the ozone layer in the earth's stratosphere and cause environmental damage such as an increase in ultraviolet rays harmful to living things, and it has been internationally decided to completely abolish them by the year 2000. (Regulations on fluorocarbons).

[0003] A number of alternative cleaning methods for Freon R113 have been proposed, but each has its advantages and disadvantages. Ultimately, it would be ideal to improve the bonding method and flux and eliminate cleaning, but it will still take time to apply it to highly reliable products, so for the time being, we will use an alternative agent to replace Freon R113. We have no choice but to adopt a method of removing such things. but,
Alkaline-based, alcohol-based, and hydrocarbon-based substitutes all have problems with quality and operational safety.

[0004] Especially when considering an existing fluorocarbon cleaning machine, it is desirable that the existing machine can be repurposed with some modification, in view of restrictions on equipment investment and equipment installation area. In that case, the R225,5FP system is the most promising among the various alternative cleaning methods, but as R225 is a new chemical substance, long-term chronic toxicity evaluation is required, and it will be applied after 1995, making it impossible to respond quickly. In addition, for the 5FP system, it is promising to change the rosin-based flux to a water-soluble flux and clean it with a 5FP/water (6% by weight) azeotropic system, but it is especially suitable for automotive applications that require high reliability. When considering printed circuit boards,
Cleanability is poor and reliability is poor. Note that in this 5FP system, the proportion of water in the azeotropic system is limited to 6% by weight, and this is considered to be because this is the concentration necessary to complete the azeotropic system.

[0005]

[Problems to be Solved by the Invention] As described above, the method of using water-soluble flux and using a 5FP-based (5FP/water) substitute for flux cleaning is particularly applicable to printed circuit boards for use in automobiles, etc. In this case, cleaning performance is poor and reliability is poor. This is because the specifications for cleaning quality of printed circuit boards for automobiles and the like are much higher than those for consumer products due to their harsh usage environment and safety. Therefore, the applicant has developed a water-soluble flux for printed circuit boards, especially those used in automobiles, and has begun cleaning some of them with water. However, this water cleaning method: ■ requires new installation or updating of equipment, ■ requires an additional drying process because the workpiece is slow to dry, and requires an increase in energy (electricity or air). It has disadvantages such as unavoidable increase in processing steps and time.

Therefore, the object of the present invention is to provide a water-soluble flux for printed circuit boards, especially for automobiles, which can be applied by modifying existing equipment, and which can be dried in a short time comparable to Freon R113. Another object of the present invention is to provide an improved cleaning composition that does not require an increase in processing steps.

[0007]

[Means for Solving the Problems] According to the present invention, the above-mentioned object is characterized in that it consists of about 85-90% by weight of pentafluorinated propanol (5FP) and 10-15% by weight of water. This can be achieved by a cleaning composition. The cleaning composition according to the present invention can be easily prepared by mixing 5FP and pure water to the above composition and stirring.

Further, the water-soluble flux to which the cleaning composition according to the present invention is applied is not particularly limited, but typical examples thereof include, for example, Japanese Patent Laid-Open No. 2-67796, which the applicant has already filed. Examples of the water-soluble fluxes described in 2.1 include water-soluble fluxes in which ethylene glycol or the like is blocked with an alkyl group. Furthermore, the actual flux cleaning can be advantageously carried out using existing cleaning equipment, preferably in conjunction with a water separator to maintain an optimum moisture concentration range.

[0009]

[Operation] The present invention enables the cleaning of printed circuit boards for automobiles, etc., which require particularly high reliability, by making it possible to reuse existing fluorocarbon cleaning machines with a simple modification, and to comply with fluorocarbon regulations in a short period of time. (% by weight) system and found a new blending range of 5FP/water.

[0010] Specifically, the present inventors have
3197 A 2-type comb-shaped electrode based on Section 6.8 was spray-coated with automotive water-soluble flux and then soldered, and the same electrode was boiled with a conventional 5FP single item and an azeotropic cleaning agent of 5FP/water (6% by weight). , cold bath, steam cleaning. After that, an insulation resistance test using the applicant's original method, that is, a high-temperature, high-humidity insulation resistance test for automotive printed circuit boards (40°C, 95RH%) was conducted.
Measure the insulation resistance of the same electrode (40℃, 95RH%, DC 100V voltage applied, left for 96 hours).
When V voltage was applied), all of them caused insulation failure due to insufficient cleaning, and it was found that it was difficult to apply them to fields with harsh usage environments (insulation resistance: 1010 Ω or more) such as automotive printed circuit boards.

However, since 5FP/water (6% by weight) has higher insulation resistance and improved cleaning quality than 5FP alone, it is necessary to use 5FP to further improve cleaning quality.
/Water (6% by weight) We thought that it would be better to increase the amount of water added. Therefore, when water was gradually added to 5FP/water (6% by weight) and the cleaned printed circuit board was evaluated using the same insulation resistance test as described above, insulation defects improved when the amount of water added was 10% by weight or more. I found that it can be done.

However, if too much water is added,
It is expected that the drying time of the workpiece after cleaning will be longer.
When considering repurposing existing Freon cleaning machines, there must be restrictions on the amount of water added. Therefore, the present inventors prepared test pieces of printed circuit boards, immersed them in various concentrations of 5FP/water, and measured the drying properties of the attached cleaning liquid using a gravimetric method. As a result, the drying properties (
It was confirmed that the blending ratio of water to 5FP, which maintains a drying time (drying time: 45 seconds or less), is 15% by weight or less.

[0013] From the above, there is a water addition amount range that simultaneously satisfies both the cleaning characteristics required for automotive use and the drying characteristics that make it possible to reuse existing Freon cleaning machines. ~15% by weight.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the cleaning composition of the present invention can be advantageously used to remove water-soluble flux from printed circuit boards using existing cleaning equipment. An example of this usage will be explained with reference to FIG. 1 attached. The illustrated solvent washer is common in this field, and has a three-tank structure: a boiling tank 1, a cooling bath 2, and a steam tank 3. It also has a solvent recovery corrugated pipe 5 for recovering volatile solvents.
and a water separator 6 for separating the recovered solvent from water.
Equipped with The water separated by the water separator 6 is removed as waste water, while the 5FP returns to the cold bath 2 via the recovery pipe 8. The solvent in the cold bath 2 can overflow into the boiling tank 1 as shown by the arrow in the figure, and the solvent in the boiling tank 1 can overflow into the steam tank 3 via an overflow pipe (not shown). It is. A work to be cleaned (not shown) is placed in a cleaning solution boiled by a heater 7 in a boiling tank 1 and in a cold bath 2.
The cleaning liquid is sequentially immersed in the cleaning liquid, and then the cleaning liquid is heated and evaporated by the heater 7 in the steam tank 3, and then dried in the cleaning liquid.

Although the illustrated solvent cleaning machine uses only one water separator 6, there are particular environmental concerns.
If atmospheric moisture is expected to be taken up, it is desirable and recommended to install independent water separators in each of the boiling, cooling, and steaming baths. This is to remove excess suspended moisture taken into each tank from the atmosphere from the vapor-liquid equilibrium diagram of 5FP and water.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Example 1 A type 2 comb-shaped electrode based on JIS Z 3197 Section 6.8 was used, and after polishing it, a water-soluble flux having the following composition was foamed and soldered using an automatic soldering machine. did. Composition of water-soluble flux Terminal alkyl group polyether 10.0% Methylamine hydrochloride 1.
0% organic acid
3.0% isopropyl alcohol
After completion of 86.0% soldering, the board was introduced into the solvent cleaning machine of FIG. 1 and subjected to boil cleaning, cold bath cleaning, and steam cleaning using a cleaning composition having the composition shown in Table 1 below. The cleaning conditions are as follows: Boiling cleaning Cold bath cleaning by immersion in a boiling tank at 80°C for 10 seconds
Steam cleaning by immersing in a cold bath at 20°C for 10 seconds. Holding in an atmosphere of solvent vapor for 10 seconds. After steam cleaning, the insulation resistance of the substrate was immersed in a 100V D at 40°C and 95% relative humidity (RH).
C voltage was applied and the measurement was carried out in a constant temperature and humidity chamber. This measurement was performed immediately after steam cleaning and after 96 hours of humidification (40°C, RH9).
The experiment was carried out in two parts: 5%, DC 20V applied). The measurement results obtained are shown in Table 1 below. For comparison, a blank test was also conducted without applying flux, and the insulation resistance values measured at that time were 4.0 x 1013 (Ω) immediately after steam cleaning, and 1.0 x 1013 (Ω) after 96 hours of humidification. It was .7×1010 (Ω).

Subsequently, a test piece (20 mm x 30 mm) of a printed wiring board made of glass epoxy was cleaned using the same cleaning composition as above and under the same cleaning conditions. Subsequently, this substrate was allowed to stand at room temperature, and the time (drying time) required until the amount of the cleaning composition remaining on the substrate surface became zero was measured. The measurement results obtained are shown in Table 1 below. Example 2 The procedure described in Example 1 above was repeated, but in this example, the 5FP was reduced from 90% to 85% by weight and the water was reduced from 10% to 15% by weight, as shown in Table 1 below. The amount was increased to % by weight. The measurement results obtained are shown in Table 1 below. Comparative Examples 1 to 4 The method described in Example 1 was repeated, but in this example, for comparison, the composition of the cleaning composition was outside the scope of the present invention. The measurement results obtained are shown in Table 1 below.

[0018]

[Table 1]

[0019]

According to the present invention, as understood from the above explanation, as a result of forming a cleaning composition from 85 to 90% by weight of 5FP and 10 to 15% by weight of water, the printed board surface The water-soluble flux can be completely washed away, and thus a substrate surface having high insulation resistance can be obtained. In addition to these effects, according to the present invention,
The cleaning composition is not flammable, so it can be used safely, existing equipment can be used as is or after minor modification, it can be dried at room temperature, and no additional drying process is required, reducing processing time. This also has the effect of avoiding an increase in power consumption.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of a solvent cleaning machine.

[Explanation of symbols]

1...Boiling tank 2...Cold bathtub 3...Steam tank 5...Solvent recovery pipe 6...Water separator 7...Heater 8...Recovery tube

Claims (2)

[Claims] 1. A cleaning composition comprising 85 to 90% by weight of pentafluorinated propanol and 10 to 15% by weight of water. 2. The cleaning composition according to claim 1, which is used for cleaning water-soluble flux used for soldering printed wiring boards.