Automated Selective Dispensing Contact Type

Adhesive Viscosity (cps) Thixotropic Index (1 10) Pot Life Cure Schedule 

Source Epoxy Technology tec mical data sheets.  

The number of dots that can be dispensed per unit of time also depends on viscosity. The use of low-viscosity adhesives increases the number of dots that can be dispensed. However, there is a tradeoff between the speed at which the adhesive can be dispensed and the speed of device placement. Most automated component-placement equipment operate faster than adhesive-dispensing equipment. A comparison of the effect of viscosity on dispensing and placementtimes is shown in Table 4.19 for an 86-lead plastic-encapsulated leadless chip carrier (PLCC).  

Automated dispensing is used for the application of die-attachment, surface-mount, and underfill adhesives. 

The pattern for rectangular devices is somewhat more complex as shown in Fig. 4.9. The major line should be centered and its length should be the difference in length between the sides of the chip. The four remaining 

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A wide variety and numerous suppliers of automated dispensing equipment are available as listed in Table 4.22. An important consideration in selecting an automated, contact-type dispensing system is the pump used in the system, of which there are three types time-pressure, auger, and linear piston or positive displacement. " ... 

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