SMT solder paste process and red glue process are two key processes in electronic manufacturing, the main difference lies in the material characteristics, process purpose and applicable scenarios.The following is a detailed analysis:

I. SMT solder paste process

1. Definition and principle

Definition: The solder paste process is the core process of Surface Mount Technology (SMT), in which electronic components are soldered on the surface of printed circuit boards (PCBs) by means of a mixture of solder powder, fluxes and adhesives in the form of a paste.

Principle:

Printing: A stencil is used to evenly coat the PCB pads with solder paste.

SMD: Equipment accurately mounts the components onto the solder paste.

Reflow soldering: The high temperature melts the solder paste and forms a strong electrical connection after cooling.

2. Characteristics

Conductivity: The solder paste cures to form a conductive solder joint, achieving both electrical and mechanical connections.

Reversibility: When the soldering is defective, it can be remelted by high temperature and repaired by solder sucker.

Applicability: Suitable for mass production, especially for high-density components (e.g. mobile phones, routers).

3. Advantages and disadvantages

Advantages: firm welding, high reliability, strong repairability.

Disadvantages: complex process, need to strictly control the printing parameters, reflow temperature profile, high cost of equipment.

II. red glue process

1. Definition and principle

Definition: red glue is a thermosetting epoxy resin adhesive, used to temporarily fix the components to prevent high temperature or other processes to fall off.

Principle:

Dispensing: the red adhesive coated in the PCB pads or the bottom of the component.

Curing: The red adhesive is hardened by reflow soldering or oven heating to fix the components.

Subsequent soldering: wave soldering is usually required to complete the final electrical connection.

2. Characteristics

Non-conductivity: only play a role in fixing, do not participate in the electrical connection.

Irreversible: red glue can not be remelted after curing, need to be physically removed.

Low cost: suitable for small batch or plug-in components more scenes (such as automotive electronic sensors).

3. Advantages and disadvantages

Advantages: simple process, low cost, can reduce the use of jigs.

Disadvantages: bonding strength is affected by temperature and humidity, easy to drop parts; welding quality is lower than solder paste, not applicable to high-density design.

III. Core differences

IV. the application scene selection

Priority selection of solder paste process:

High component density (e.g. smart phones, chip modules).

Long-term reliability (e.g. medical equipment, automotive electronics).

High-volume production (significant economies of scale).

Consider red glue process:

Small orders or sample production, need to reduce cost.

Components are large and widely spaced (e.g., traditional home appliance control boards).

Need to avoid components falling off during wave soldering (e.g. through-hole inserts coexisting with SMD).

 Summary

Solder paste process is the mainstream soldering method in electronic manufacturing, taking into account the efficiency and quality; red adhesive process as a complementary, in specific scenarios to balance the cost and process requirements.The actual choice should take into account the complexity of the product, production scale and reliability requirements.