The purpose of this paper is to identify and eliminate the shortcomings of the epoxy molding compound (EMC) thawing process and prevent mishandling of the molding compound, such as using the wrong molding compound, incomplete thawing of the molding compound, or expired shelf life.
This article developed a molding compound handling automation solution for high-risk issues, such as molding compound traceability barcodes, thawing cabinet thawing chamber access control systems, molding compound status automated monitoring graphics, and batch transaction systems were upgraded to link EMC status and product name. Overall, this prevents misjudgment or dereliction of duty due to manual operations.
This project eliminates possible mishandling of molding compounds associated with EMC thawing and avoids potential financial losses due to poor batch processing.
Thawing is an important step in the EMC preparation process before plastic molding, which can prevent the deterioration of the molding compound and the deterioration of material properties, which affects the quality and reliability of integrated circuits (ICs). EMC is sensitive to external environmental conditions, as the degree of cure is affected by environmental conditions.
EMC curing is usually divided into four stages, and thawing is the last stage of EMC transport to warehouse refrigeration stage B after leaving the factory, as shown in Figure 1.
To thaw the molding compound, remove the EMC from cold storage at 5°C or lower, and go through a staged curing process, typically thawing in an indoor environment for 24 hours, typically set at 23°C ± 3° (21°C). °C to 24°C), relative humidity 40 to 55% RH (41% to 51%), as shown in Figure 2. After that, the EMC was loaded into a compression molding machine for compression molding according to the prescribed floor life. Once the shelf life of the open bag expires, it is considered that the EMC has passed the shelf life and should be disposed of properly. The main purpose of thawing is to prevent moisture from entering the sealed bag. If not dehumidified, the molding compound will cause processing defects such as package voids, blistering, or incompleteness. Moisture can also cause reliability issues such as pad or lead corrosion, delamination, or popcorn when heat is applied during post-package or customer manufacturing.
1.1 Improper handling of molding compound
Improper EMC handling includes using wrong EMC material, EMC past shelf life, and incomplete EMC thawing. Using the wrong EMC material means using a different EMC than the product requires, which may be the wrong type of material or the wrong particle size. EMC expired shelf life refers to the use of materials beyond the specified open bag shelf life. Incomplete thawing refers to the situation where the material is used in advance before the thawing time has expired.
Judging from the trend of EMC mishandling accidents, in the fourth quarter of 2018, one EMC processing failure accident that passed the shelf life was recorded, and an incomplete thawing accident occurred in the first quarter of 2019, as shown in Figure 3.