Solder performance evaluation methods：solder bar

Solder bars are pure metal alloys without flux.

① Chemical composition of leaded solder alloy (Sn63A).
The chemical composition of the leaded solder alloy (Sn63A) covered by this standard shall conform to the requirements of IPC/EIAJ-STD-006A standard, as shown in the table below.

Alloy Designation	Main Components (% wt)	Impurities (% wt, not greater than)
Sn63A	Sn: 61.5 ~ 63.5 Pb: Balance	Sb: 0.1 Cu: 0.05 Bi: 0.08 As: 0.02 Fe: 0.02 S: 0.002 Zn: 0.002 Al: 0.005 Cd: 0.005 Ni: 0.01 Ag: 0.05 Au: 0.05

Solder Bars

②) Chemical composition of lead-free solder alloy (SAC305).

The chemical composition of the lead-free solder alloy (SAC305) covered by this standard shall conform to the requirements of JS/Z3198-2005, as shown in the table below.

Alloy Designation	Main Components (wt%)	Impurity Elements (wt%, not greater than)
SAC305	Sn: Balance Ag: 2.7–3.5 Cu: 0.3–0.7 Sb: ≤0.1 Bi: 0.08 As: 0.02 Fe: 0.02 Pb: ≤0.1 Zn: 0.002 Al: 0.005 Cd: 0.002 Ni: 0.01 Au: 0.05

① Dimensional requirements.

The permissible dimensional tolerances for wire and thread-shaped brazing alloys with a resin core shall conform to the specifications in Table 2.8.
The dimensions of rod, strip, powder, BGA ball, and other shapes of solder are determined by negotiation between the supplier and the customer.

②Surface quality requirements:
The surface of the solder alloy should be smooth and clean, free from cracks, oil stains, and other defects.

Table 2.8 Outer Diameter and Tolerance Dimensions of Silicon Bronze, Phosphor Bronze Needle Alloys (Unit: mm)

Diameter φ (mm)	Tolerance (mm)
φ ≤ 0.3	±0.02
0.3 < φ ≤ 0.8	±0.03
0.8 < φ ≤ 2.5	±0.05
2.5 < φ ≤ 6.0	±0.10

Solder Bars

①Resin-cored solder alloys:

Requirements: The characteristics of the resin core flux should conform to the requirements of J-STD-004A.
Flux percentage content: For fluxes used in resin-cored wire and rod solder alloys (not solder paste), the mass percentage should be determined according to the relevant provisions of IPC/EIA J-STD-006A.
Uniformity and continuity of the flux: Unless otherwise specified, solder alloys with flux cores can be of any structural shape, but their cross-sections should be continuous, uniform, and symmetrical. The internal flux should be uniform and continuous, without any breaks or gaps. If possible, the cores at both ends of the solder should be sealed using appropriate methods to prevent flux leakage.

② Pre-fluxed solder alloys:
Unless otherwise specified, the pre-fluxed solder alloys must have a dry, non-sticky flux coating. At temperatures below 25℃ and humidity below 60% RH, the solder alloys should not stick together.

The wettability requirements for brazing alloys shall comply with the requirements of GB/T2423.32.

The basic characteristics of brazing alloys commonly used by the company are shown in Table 2.9.

Table 2.9 Basic Properties of Commonly Used Needle Alloys

Alloy	Characteristics	Melting Temperature (°C)	Density (g/cm³)	Tensile Strength (MPa)	Elongation (%)	Hardness (HV)	Electrical Conductivity (μΩ·m)
Sn63A		183	8.64	52	34.5	12.8	11.0
SAC305		217-219	7.376	42.6	38	17	13

Fluidity after melting the liquid solder.

Important requirement: When low-temperature welding materials are used for wave soldering, the welding temperature has an impact on the quality of the welded joint. The weight of each welding strip must be controlled below 5kg.

Oxidation resistance: At a specific capacity of wave soldering tin liquid height less than 15mm, in an air environment, the tin slag produced in 24 hours is less than 8kg.

Reliability

The reliability meets the company's product reliability quality requirements.

The alloy composition principle of the welding strip must remain consistent with the welding pipe.