JPS59211566A - Electroless solder plating method - Google Patents

Abstract

PURPOSE:To form a plating layer having excellent adhesion and uniformity in the stage of performing a plating treatment in an electroless solder plating liquid consisting of tin borofluoride, lead borofluoride, thiourea and a reducing agent by dividing the operation to >=2 stages and increasing successively the concn. of the metallic components in the plating liquid to be used. CONSTITUTION:A plating operation for solder plating on the surface of a material to be treated by using an electroless solder plating liquid is accomplished by dividing the operation to at least two stages. More specifically, the electroless solder plating liquid contg. tin borofluoride, lead borofluoride, thiourea and a reducing agent of metallic salt ion and a surface active agent according to need is used as the electroless solder plating liquid and the concn. of the metallic components of said Sn and Pb is made 1/2-1/10 of the concn. of the metallic components in the liquid to be used in the final plating. The grain of the deposited solder plating layer is fine and the Sn-Pb solder plating layer having adhesion and uniformity over the entire part of the material to be treated is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying non-decomposition solder plating.

Soldering has come to be widely applied to parts of electronic equipment, precision equipment, automobiles, etc. in recent years for the purpose of preventing rust and improving the efficiency of repair work for other equipment parts. It was.

There are two methods of solder plating: electroplating and electroless plating, but the electroplating method is used when it is not possible to apply the solder uniformly due to the cedar wood of the object to be plated, especially on pipes. A crossroads such as a state? However, it was not possible to perform electroplating on the inside of a plated body having voids inside the body or on the inside of the body.

Furthermore, it was not possible to plate electrically non-short-circuited parts such as drum plating bodies and printed Igl circuits that do not have electrical 4% L properties.

In the non-mechanical soldering method, solder plating can be applied to the inside of the structure even though the body of the receptacle has a cavity with a complicated structure, and it is also non-electrical. Solder plating can also be applied to broken plated parts and electrically non-short-circuited partial pressure.However, the conventional non-alpha solution soldering method requires a small plating speed and a board temperature that increases +u. The plating thickness was 3 to 4 μm, and the adhesion of the solder plating scraps to the substrate was not necessarily sufficient.Especially, when the plating speed was increased and the plating thickness was increased, the finished surface of the plating was a coarse crystal surface. As a result, the adhesion was further reduced.

The present inventor provides an excellent method in which the particles of the deposited solder plating layer are fine and can be plated with good adhesion, and electroless solder plating with a good gradient is uniformly applied to the inside and outside of a broken body. As a result of the grinding, the concentration of the plating bath used for each step was increased to a level higher than the concentration of the plating bath used in that step, and the concentration of the plating bath used in that step was increased to zero By doing this, the solder plating becomes more solid, has better adhesion, and the knowledge that thicker solder plating is superior led to Noichimoto's completion.

That is, the gist of the present invention is to solve the problem in at least two stages.
This is a patented solder plating process in which the metal component IA of the plating bath is successively increased in stages.

In this way, the electroless solder plating is carried out in several steps, and the concentration of the metal component in the first electroless solder plating bath is the concentration of the final step plating bath. It is preferable. Success 1: j, Yamagai of the plating bath on the floor is the final ↓ Compared to that of the plating bath at Chinan, the thickness of the electroless solder plating at Hatsume is too thin and undesirable. (・.

For the bath, the main ingredients are the conventional chloride solution, lead chloride, and thiourea. No patent application filed.
E l=# solder plating bath is used.

The paper-free soldering bath invented by the inventor contains tin borofluoride, lead fluoroboride, hydrogen borofluoride, thiourea, reduction cutting, and #surfactants depending on safety.
If this P+lF-free solder plating bath is used instead of the plating bath whose main components are crane chloride, lead chloride, and thiourea, the plating bath can be made at a lower temperature.
It is easy to prepare, and when the plating solution is infiltrated into the plating bath during the fast dissolving process, precipitation of the plating bath components due to a decrease in the humidity of the plating bath and the accompanying precipitation are avoided. It is advantageous in that such problems can be avoided, the particles of the resulting plating layer are fine and have good adhesion, and the plating does not peel off even when bent.

Although it varies depending on the humidity and bath composition of the non-resistance bath in which the object to be plated is immersed in the first stage, the plating bath has an odor at room temperature to prevent precipitation of the plating bath components. If a precipitate is to be precipitated, the precipitate p
It is preferable to raise the temperature to a higher temperature until the sludge disappears to prevent problems with the plated surface due to precipitation. The time for immersing the limb-plated bale in the plating bath in step w is not particularly limited, but 5 to 30 seconds is sufficient.

Since the non-explosion ψ is constructed as described above, it is possible to apply solder plating to the curved body with a smooth and even fit, and with excellent adhesion.

This is due to the following reasons. In other words, in the case of electroless electrolyte, lead, which is a component of the seventh bath, does not have self-catalytic properties, so (/r) chemical placing reaction with the object to be plated, ( b) Reduction reaction by the primary agent, (c) Local 'ai based on the microscopic local potential difference of these anti-LLs.
It is assumed that electrolytic deposition is carried out by means of a current. The anti-LE that occurs immediately after immersing a solder plate (gold) in a solder plating bath is a chemical comparison of (a), but this reaction is caused by the large number of cracks that exist on the surface of the solder. Since the plating is carried out between the local anode and the local cathode, the reaction rate is high and the superior plating increase results in a porous film.

As a result, if the plating plate is immersed in this electroless plating bath for a long time, the crystals precipitated on the local surface will be held together and become coarse crystalline, and the plated surface will have a rough finish and curves can be avoided. do not have.

The present invention is designed to quickly complete the chemical 14 battles in (a) at the beginning by performing T&M in multiple stages from a thick plating bath to a thick plating bath. 1. Next stage finale
Since the process proceeds to dipping, the reaction is terminated before the microcrystals formed on the forked surface formed by the first dipping are grown, and then the above (b) and (c) are completed in the second dipping step. ), the solder particles are precipitated without a layer of plating, so the resulting plating layer is dense and smooth, has good uniformity, and has excellent adhesion.

Stage number F of transition from dilute licking bath to rich licking bath
1 The purpose is usually accomplished in two steps.

Furthermore, according to Futomei, even if the inside of the covered body is covered by an outer wall due to the fabrication of seven, the inside of the body, such as the inside of a pipe or a serpentine pipe, or the structure of a cedar-like structure, Since the inner part of the solder plate has a free melting bath, it is possible to apply a sufficient heatless soldering bath to the inner circumferential side surface of the empty hole.

The present invention will now be described with reference to examples, but the present invention is not limited by these traps.

Example 1 A free solder plating bath having the following composition was prepared.

Tinn borofluoride (J, 1 mol/l fluoroborate 0.04tt Thiourea
2.0μ Sodium hypophosphite 0.2〃EDTA
O,05N nonionic field activator
0.5 if'/l (polyethylene glycol nonyl phenol ether) Dilute a part of the solder plating bath (this is called the plating base bath) with water to make the plating base. Ushaku bath with a concentration of 1k or 100 for the amount of sukiyaki.
“I made 4.

Remove brass & (100x100xO, 4m) with
After washing with acid and water, the first step is to immerse the plate in the dilution bath for 10 seconds at room temperature (18°C) to apply a thin, non-electro-applied Kendamezuki j- to the surface of the body to be plated. In the second step, this brass plate was
ii) When exposed to the Metsusa raw bath at 80°C for 15 minutes, the alloy composition was found to be Sl 569, p b 4a 96
Then, a pile of solder plating with a thickness of 2.8μI11 was deposited. The intersection of the diagonals of the plated brass plate (
The thickness of the 4 points at a distance of 4 Qll from the center point) and the center point on the diagonal) is 1
lI! iu did it.

As a result, the center point is 2.6μm, the other points are 2.9μIn, 3.0μrus2.8μ”%2.7μm, respectively.
The deviation value from the center point was 0.1/0.4 μIn.

Also, the size of Metsu@CrystalHani+￥llI is 0.5
~2.0 μIn was found.

Comparative Example 1 A brass plate similar to that used in Example 1 was placed in the base bath used in Example 1.
No-t441rf solder plating was carried out using the same lead as in Example 1 except that the operation of f-f was not performed.

The alloy Kazsei of fj @jψ is Sn 59 circles, ~1
In addition, the thickness of the plated yellow plate was measured according to Example 1, and the center point was 2.92 m1 on the diagonal line. Point Yoshi 4 crpr cr) i (The plating thickness with 4 pieces is 8.
2.3.6.2.4.4., 2 μm, 5th hole, center point (119) was −0.5 to 1.3 μm, 4 points.

Comparing Example 1 and ratio V, ← 111, it is clear that 1 blunder example 1 is a 1 superior tame j needle attack! The crystal has a softness of 11, and the thickness is slightly 1, and the adhesion is good, and the thickness of the plating layer has a small deviation from the center point, and the thickness is flat. It was observed that the results were uniform.

Staining tZ12 A conventional non-soldering bath (hereinafter referred to as Metsu@raw bath) having the following composition was prepared.

Chloride 207/13 Chloride ship 11// Thio original 110//l Sodium hypophosphite 209/IEDTA,
'30 N Seratin
1 〃 p HrIl, :h adjustment (8Cl) ¥) Hl,
The unprocessed sake with 211 V) was humidified at 90℃ to make a completely transparent liquid, and a part of it was diluted with water to make Metsuguchi (
Bath C, play rC so that the error rate becomes 1.

0 u<Hjke~;

Finally, a brass plate of the same size as that used in Example IK was treated with HIJ, and as the first step, it was immersed in a dilution bath for 15 seconds at 18°C. As a result of step 7, it was dense and extremely thin, similar to brass (the plating layer was excellent).

Do not wash this brass plate with water.
When the alloy was immersed in IMi for 15 minutes at 90°C in a bath marked with ", the alloy composition was sn 52 The solder thickness was 1-7.The thickness of the plated layer on the plated yellow lead surface was measured using the same method as in Example 1, and it was found to be 2.4μ■ at the center point. 1. At a point 4 cm away from the center point on the diagonal line, 2.8.2, 'l, 2.7.
It is 2.9μm, and the deviation from the center point is 0.3~
It was 0.5 μm.

Comparative Example 2 A brass plate similar to that used in Example 2 was washed under the same conditions as Example 2, except that the same brass plate as used in Example 2 was not immersed in the dilution bath as the first step. Electrolytic solder plating was performed.

The roughness was 5 to 10 μm, and the surface of the plating layer was clearly rough. When the thickness of the plating layer on the brass liR surface was determined according to Example 2, it was 2.6 μm at the center point, and 8.6 μm at a distance of 4 crn from the center point on the diagonal line.
2.4 μm, (7.9 μm 12° 5 μm, deviation value from the center point -1.7 μm) to +1.0 μm.

Comparing Example 2 and Comparative Example 2 from the above, it can be seen that the grain size of the @ layer obtained in Example 2 is finer than that of Comparative Example 2, and 6. 1. If the difference value is small, dense Xi a VC is excellent, smooth and uniform, 11
I was praised.

Example 3 The same plating stock as used was divided into 3 parts, a part of which was left in the plating IJJ (bath), and the remaining part was diluted to the concentration of i.

The same brass plate as was used was first diluted into the diluted plating bath for 10 seconds at normal humidity in the diluted plating bath (as the second step). It was immersed in AI for 30 seconds at 30°C, and then immersed in a plating paper bath for 15 minutes at 80°C as the third step.

The textured layer is extremely smooth and smooth, with a thickness of 2.8 μm and 55% alloy, PB45.
It was 96.

The fruit! ]t? 4 9.6 Take the same amount of unblended sake as used in Example 162 and dilute part of 1 and 7 with water to make 1 to 7.

In the first step, a vibrator with an outer diameter of 25 cm and a wall thickness of I/5 sides processed into a cylindrical shape was placed in this diluted plating bath, after which it was removed from TJtn, washed with water, washed with water, washed with water, and then placed at normal humidity. 1
It was soaked for 5 seconds, and then soaked for 114 hours at 80°C for 15 minutes in Metsusa unblended sake as the 21st batch.

After immersing the pipe in oil, I placed the pipe inside the pipe and found that it had been solder-plated in a well-protected manner.

Patent issued by 1 person, Takumi Shikisha Toisakakin 1°C Bench Attorney W. Tsukasa Sono

Claims (1)

[Claims] (13) The electroless solder plating process is carried out in at least two stages, and each time the step A is performed, the concentration of the electroless solder plating bath is increased. Electroless sharding method (2) In claim 1, i
``W solder plating method characterized by carrying out the electroless plating process in two steps'' (3) Claim 2 states that gold & la in the electroless solder plating bath in the first step. Free solder plating method characterized in that the yield concentration is E to L in the second stage electroless plating bath (4) Range of 6,000 - ice Item 1 1. A non-1i8 solder plating method, characterized in that the non-411 solder plating bath contains tin borofluoride, tin borofluoride, thiourea, and a reducing agent.