JPH02104493A - Solder for connection - Google Patents

Abstract

PURPOSE:To assure the reliability of solder connection over a long period of time by incorporating a specific ratio of either one or two kinds of Zn, Mg, and Mn into Sn or Sn alloy solder. CONSTITUTION:Either one or >=2 kinds of the Zn, Mg and Mn are incorporated at 0.1 to 2.0wt.% in total into the Sn or Sn alloy solder. Solder embrittlement is prevented in this way without deteriorating the wettability and appearance regardless of the kinds of a lead material. The long-term reliability of soldering is thus assured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improved connecting solder used for preliminary soldering of electrical and electronic component leads or for connecting to a board, etc., and particularly relates to improved solder wettability and appearance. This ensures long-term reliability of solder connections without deteriorating the solder connection.

[Conventional technology]

Generally, Sn or Sn alloy solder is used for mounting electrical and electronic components onto wires and printed circuit boards. For example, semiconductors, which are electronic components, are soldered to S n -10v1 by electroplating or dipping in advance to ensure proper soldering properties when mounted on a board after packaging.
%Pb alloy solder is attached, and this is soldered to a printed circuit board (PCD) etc. by a mounting manufacturer using eutectic solder (Sn-40W).
1% Pb alloy).

When using through-holes for this connection, after setting them on the board, connect by spraying molten solder from the opposite side of the component mounting area (flow method), and in the case of surface mounting, screen the connection part of the board in advance. The best method is to apply a paste-like solder by printing or the like, place component leads on top of it, and then melt the solder using infrared rays or the latent heat of organic solvent vapor to make connections (reflow method).

[Problem to be solved by the invention]

Components connected using the above method must remain stably connected for a long time, but depending on the lead material of the component being connected, fragile phases or voids may form at the interface between the solder and the lead, making the connection with the solder difficult. If it becomes insufficient or in severe cases, accidents may occur where parts are missing.

Examples of this include embrittlement due to high concentration of P in phosphor bronze, Ni and Fe deposited alloys such as Cu-Ni, Cu-F
Copper alloys for embrittlement and precipitation strengthening of alloys such as e, Cu-Ni-3n, etc., such as Cu-Cr-Zr, Cu-Ni-8i
It is known that alloys such as these are embrittled. Among these alloys, embrittlement can be prevented with phosphor bronze by lowering the Pa degree, and with other alloys, embrittlement can be prevented by adding small amounts of Zn or Mg, and furthermore, by applying base plating to the leads, etc. Countermeasures are known. However, there are cases where the improvement is insufficient or where the inherent properties of the alloy cannot be fully utilized.

Although the problem of solder embrittlement has become more serious in recent surface mounting on boards, lead materials for electronic components are made of a variety of materials depending on the type and manufacturer. This is undesirable from the viewpoint of reliability of the system as a whole. In particular, higher integration of semiconductors and smaller packages increase thermal stress, which tends to exacerbate the problem.

[Means for Solving the Problems] In view of this, and as a result of intensive studies, the present invention has developed a connecting solder that can prevent the solder embrittlement described above regardless of the type of lead material.

That is, the present invention provides Sn or Sn alloy solder with Zn, Mg
, Mn, a total of 0.1 to 2v1 of one or two or more types
%.

[For production]

In the present invention, Zn,
One or more of Mg and Mn in a total of 01 to 2.
(The lv1% content was made to prevent the solder from becoming embrittled regardless of the type of lead material. Although its mechanism of action is not necessarily clear, generally Cu alloy side This phenomenon is believed to be based on the so-called Kirkendahl effect, in which voids are formed at the interface due to extremely slow diffusion of additive elements into Sn, and the addition of Zn, Mg, and Mn, which have high diffusivity, causes them to diffuse into the voids. This seems to be to eliminate voids.

Therefore, Zn is contained in Sn or Sn alloy solder.

A total of 0, l of any one or two or more of Mg and Mn
~2. The reason why Ov1% was included was because if it was less than 0.1w1%, a sufficient effect could not be exhibited.2. This is because if the solder melting point exceeds GWI%, the melting point of the solder increases, fluidity decreases accordingly, and slag is generated after soldering, which is not preferable.

The method of applying the solder of the present invention includes melting the above-mentioned connection solder and spraying it onto the object to be soldered, or immersing the solder object in a molten bath of the connection solder, or the above-mentioned method. The connection solder may be made into a paste, screen printed on the object to be displayed, and then the connection solder may be melted.

〔Example〕

Commercially available Corson alloy (Cu73.2) with a thickness of 0.25 mm
w1%N i -0,75w1%Sn) to S n -1
0WI%Pb alloy solder was applied to a thickness of about 5μ by the dipping method, and this was applied to a width of 10+nl11. After cutting to a length of 30 mm, MH820V flux manufactured by Tamura Manufacturing Co., Ltd. was used in a eutectic solder bath having the composition shown in Table 1, and soldered at 230°C for 10 minutes.
After applying solder by dipping for a second, the solder viscosity and solder appearance were examined, and a test for solder embrittlement was conducted. The results are also listed in Table 1.

Solder wettability is determined by wetting time using a meniscograph.
The appearance of the solder was determined in accordance with the Monthly SC5033 Condition B method, and a wetted area of 95% or more is indicated by ◎, 90% or greater is indicated by ○, and 90% or less is indicated by Δ, and those with a good appearance are indicated by ○. Solder embrittlement was determined by heating the solder in a constant temperature bath at 150° C. for a predetermined time and then performing a twisting peel test to determine the heating time until peeling occurred.

As is clear from Table 1, Zn, Mg.

Comparative solder N made of 5n-P alloy without addition of Mn etc.
Although α11 and Zn, Mg, Mn, etc. are added, the comparative solder Nα12. 14°16 has a small effect, whereas Zn and Mg.

The solder Nα1 to Nα10 of the present invention to which an appropriate amount of Mn or the like is added has good solder wettability, appearance, and solder embrittlement. On the other hand, comparative solder Na1 with excessive addition of Zn, Mg, and Mn
3. 15. 17. It can be seen that although the solder embrittlement of No. 18 was good, the solder wetting time was long and the solder appearance was not good.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent solder embrittlement, which is important for solder connections, without deteriorating solder wettability or appearance, and it is possible to prevent solder embrittlement, which is important for solder connections, by paying special attention to the materials of individual components when mounting semiconductor printed circuit boards. This makes it possible to perform soldering without any process, and has significant industrial effects, such as ensuring long-term soldering reliability.

Claims (1)

[Claims] (1) A connecting solder characterized in that Sn or Sn alloy solder contains one or more of Zn, Mg, and Mn in a total amount of 0.1 to 2 wt%.