Dispensing patterns

Simons FE, Peterson S, Black CD Epinephrine dispensing patterns for an out-of-hospital population a novel approach to studying the epidemiology of anaphylaxis. J Allergy Clin Immunol 2002 10 647-651. 

Bressler, L.R. Geraci, M.C. Feinberg, W.J. Pharmacists attitudes and dispensing patterns for opioids in cancer pain management. J. Pain Symptom Manage. 1995, 3 (2), 5-20. 

The inherent simplicity of the jetting mechanism enables it to adapt to a wider variety of adhesive fluids, dispense patterns, and circuit board geographies than is possible with a needle dispenser. This simplicity facilitates multiple processes using a single jetting dispenser. 

During die attach, an adhesive creates a mechanical interface between the die and substrate in a semiconductor assembly. A typical dispense pattern has intersecting lines with strategically placed dots so that after die placement, the fluid is evenly distributed (Figure 10-12). Most die attach adhesives also provide thermal and/or electrical conductivity between the die and substrate. 

Figure 4.8 Dispense pattern for a square die (> 20mni/side). (Copyright 1999, Reed Exhibition Corp., reproduced with permission ...

Figure 4.12 Dispense patterns for capillary-flow underfill adhesives Top 1 shape Middle L shape Bottom modified XP shape.

A range of fill patterns that can be used is shown in Figure 4.12. The specific dispensing pattern used depends on the shape of the part (square or rectangular) and the size of the device. 

The simple I dispense pattern is widely used for square devices. Multiple applications, however, may be needed followed by a fillet or seal at the other three sides using a fine gauge needle. A limitation of this approach is the time required to underfill large die. For die smaller than 3-mm square, a single pass usually suffices. Yet another option for small die is to apply a single dot at one edge. ... 

Katze evaluated four dispense patterns as shown in Figure 5.10. The X and the five-dot patterns were most susceptible to air entrapment. The single-dot and single-line patterns gave the best coverage. Initial coverage beneath the die was... 

Figure 5.10 Dispense patterns for no-flow fluxing underfill.

The shape and size of the devices to be bonded define dispensing patterns. Patterns for square die are simpler than for rectangular die, and patterns may vary within each category as die size increases. Simple dot dispense patterns are used for small square die (less than 5 mm per side), but the volume must be estimated so that the circular area of the adhesive will spread to the edge of the die and produce a fillet. Square die, larger than 20 mm per side, still require a center dot, but must also be supplemented with a cross-pattern and other dots in order for the adhesive to flow uniformly (Fig. 4.8). The lines should extend far enough so that, once the die is placed, its bonded surface will be completely covered. Typically, this involves... 

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