Substrate and package with micro BGA configuration
A substrate of a micro-BGA package is revealed, primarily comprising a substrate core, a first trace, and a second trace where the substrate core has a slot formed between a first board part and a second board part. The first trace is disposed on the first board part and has a suspended inner lead extended into the slot where the inner lead has an assumed broken point. The second trace is disposed on the second board part and is integrally connected to the inner lead at the assumed broken point. More particularly, a non-circular through hole is formed at the assumed broken point and has two symmetric V-notches away from each other and facing toward two opposing external sides of the inner lead so that the inner lead at two opposing external sides does not have the conventional V-notches cutting into the inner lead from outside. Moreover, the inner lead will not unexpectedly be broken and the inner lead can easily and accurately be broken at the assumed broken point during thermal compression processes.
1. A substrate of a micro-BGA package, comprising:
a substrate core consisting of a first board part and a second board part to form a central slot therebetween;
a first trace disposed on the first board part and having a suspended inner lead extended into the slot, wherein the inner lead has an assumed broken point; and
a second trace disposed on the second board part and is integrally connected to the inner lead at the assumed broken point;
wherein a non-circular through hole is formed at the assumed broken point through the inner lead, the hole has two symmetric V-notches away from each other and facing toward two opposing external sides of the inner lead.
2. The substrate as claimed in claim 1 , wherein the through hole is adjacent to the second board part to increase the length of the inner lead from the assumed broken point.
3. The substrate as claimed in claim 1 , wherein the width of the through hole between the two V-notches is not smaller than half of the width of the inner lead between the two opposing external sides.
4. The substrate as claimed in claim 1 , wherein the angle of the V-notches is not greater than 90 degrees.
5. The substrate as claimed in claim 1 , wherein the shape of the through hole is chosen from the group consisting of rhombus, square, and olive-shaped.
6. The substrate as claimed in claim 1 , wherein the first trace and the second trace are formed from the same circuitry, wherein the circuitry further comprises an external pad electrically connected with the first trace.
7. The substrate as claimed in claim 6 , wherein the first trace and the second trace are formed on a bottom surface of the substrate core.
8. The substrate as claimed in claim 1 , wherein the substrate core is a flexible film.
9. The substrate as claimed in claim 1 , further comprising a solder resist formed on the substrate core to cover the first trace and the second trace with the inner lead and the slot exposed.
10. The substrate as claimed in claim 9 , further comprising an elastomer formed on the other surface of the substrate core opposing to the surface on which the first and second traces are formed.
11. A micro-BGA package comprising a substrate as claimed in claim 1 and a chip, wherein the active surface of the chip is attached to the substrate, the chip has a bonding pad on the active surface and aligned within the slot, wherein the inner lead is broken from the assumed broken point and bonded to the bonding pad through the slot.
12. The micro-BGA package as claimed in claim 11 , wherein the first trace and the second trace are formed from the same circuitry, wherein the circuitry further comprises an external pad electrically connected to the first trace, wherein the micro-BGA package further comprises an external terminal jointed to the external pad.
13. The micro-BGA package as claimed in claim 12 , wherein the first trace and the second trace are formed on a bottom surface of the substrate core.
14. The micro-BGA package as claimed in claim 12 , wherein the external terminal is a solder ball.
15. The micro-BGA package as claimed in claim 11 , further comprising an encapsulant formed on the substrate and in the slot to encapsulate the chip and the inner lead.