Preformed solder tab

First, research and development background

In the existing SMT process, the thickness of the alloy used for soldering in the solder paste is only half of the volume of the solder paste, so sometimes the solder paste cannot provide sufficient solder amount, solder joint strength and solder coverage. The situation can not meet the requirements. Many problems, such as proper hole filling, SMT package pin coplanarity, and RF patch warpage, generally require more solder to achieve acceptable mechanical reliability.

One of the core objectives of soldering with pre-formed solder tabs is the porosity of the solder joints. When soldering some special components with solder paste, more voids will be generated, and the void ratio will exceed 25%, which will seriously affect the yield of subsequent test procedures, as well as the reliability and heat dissipation of the joint. Victaulic has achieved a major breakthrough by using a suitable proportion of flux on the surface of the soldering surface to reduce the void rate after soldering to less than 5%. It is almost unmatched in the pre-formed soldering counterparts.

Second, the advantages of preformed soldering

1. It is not necessary to change the design of the PCB to solve the problem of insufficient solder.
2, precise control of solder content
3. Compatible with standard alloy solder paste
4, reduce the need for solder paste overprint, reduce solder splash
5, reduce the proportion of flux and solder paste in the solder paste, thereby reducing flux residue
6, tape or tape-type packaging can be quickly and accurately placed through SMT placement equipment to increase production

Third, only special product introduction

Preformed soldering lugs are usually used for special requirements on the shape and quality of solder. They can be made into any shape and size to meet specific needs. Common shapes include circular gaskets, discs, rectangles and frames.
Pre-formed solder tabs with flux reduce the handling during soldering and avoid manual fluxing. The same weight per sheet ensures consistent soldering and reduces the operator's operational skills. The product has good solderability, no cleaning, low void rate and so on.

Fourth, product features

· Flux coating is uniform, the deviation does not exceed 5%;
·The size is accurate and the tolerance is less than 0.01mm;
· The surface flux is dry and not sticky;
· Tape, box and other packaging forms, easy to produce and assemble.

Five, the main push products

In addition, according to different alloy composition and special size requirements, the corresponding pre-formed soldering piece can be provided. The tolerance of length and width can be at least ±0.025mm, and the thickness tolerance can be minimized to ±0.005mm.

In order to have a better soldering effect on the solder tab, a thin layer of flux film is usually applied to the surface of the solder tab. Victaulic can produce pre-formed solderings of different sizes. The surface of the soldering surface can be coated with flux to adjust the composition of the flux coating according to different application environments.

6. Selection basis of preformed soldering piece

Assembly working temperature, environment
Material type, temperature resistance, thermal expansion coefficient of components to be welded
Surface treatment of welding parts to be welded, metal transition layer design
Physical and chemical properties of solder
Assembly process design
Solder soldering process and equipment

Seven, the choice of pre-formed soldering piece size

The location of the solder joints and the amount of solder will determine the size and shape of the preformed solder. After determining the planar dimensions (diameter, length, width), the required amount of solder can be achieved by adjusting the thickness.
Each preformed solder has a specified flash edge tolerance. Standard tolerances should be chosen as much as possible.

Eight, application areas

Preformed solder tabs are widely used in semiconductor packages such as high power transistors, high power LED lamps, and laser diode LDs. These applications include hermetic caps, RF and DC-block bonding in the optoelectronic packaging industry, laser diode die bonding, and bonding of active device chips and ceramic substrates.
Preformed solder tabs are the ideal solution for PCB assembly, automotive component assemblies, connectors and end devices, chip connections, power module substrate attachment, filter connectors, and electronic component assembly.

In the SMT operation, the amount of tin is increased locally for individual components. The best solution is to use a pre-formed soldering piece for the tape carrier, which can provide pre-formed soldering pieces of standard specifications 0201/0402/0603/0805 and 1206, and can be The exact amount of solder you need is achieved by changing the thickness while still maintaining the length and width of the solder tab.

Nine, frequently asked questions

Question 1: How to patch?
The tape can be installed to realize automatic film placement, and can also be boxed, tray mounted, or bulk, hand-paste.

Question 2: Does the SMT furnace temperature need to be adjusted?
No additional adjustment is required, and the other components are used together because the same alloy has the same temperature; only 1% to 3% of the flux has no requirement for gas output; the furnace temperature curve with extremely long baking time is not suitable for preforming. Solder pad application.

Question 3: Preform soldering and solder paste compatibility issues
If the solder paste is water-washed, the pre-formed solder tabs may be coated with flux, but the soldering effect is expected to be re-confirmed.

Question 4: Pre-formed soldering package and storage
Packaging: To reduce oxidation problems caused by exposure to air, preformed solder should be packaged in one shift.
Storage: Pre-formed solder is recommended to be sealed and stored in its original packaging and opened only when in use. Store in a non-corrosive atmosphere, dry environment, the relative humidity of the environment should be less than 55%, the temperature is recommended to be lower than 22 ° C, or stored in an inert gas.