CN101650294A - Method for testing bond strength of materials - Google Patents

Abstract

The invention discloses a method for testing bond strength of materials. The generally adopted method for measuring the bond strength is mainly a tensile test method of destructive wire bonding of double bonding points. Operating error can not be easily avoided in the actual operation, so that accurate bond strength can not be obtained. The method of the invention is different from the existing tensile test method of destructive wire bonding of double bonding points in which a lifting hook is hung in the middle of the wire. By adopting the tensile test method of destructive wire bond of a single bond point, a bonding point one and a bonding point two are measured individually, so that tension numerical value can be directly read on a tensometer. The accurate bond strength can be obtained.

Description

A kind of method of testing of bond strength of materials

Technical field

The present invention relates to a kind of method of testing, be specifically related to a kind of method of testing of bond strength of materials.

Background technology

Wire Bonding Technology is widely used solder technology.The lead-in wire bonding is realized simple, with low cost with technology, be suitable for multiple packing forms and occupy an leading position in connected mode.90% of present all package pins adopt the mode of lead-in wire bonding.And the quality of lead-in wire bonding directly has influence on the performance of components and parts and the yield rate of encapsulation.So it is very necessary that para-linkage intensity is carried out objective and accurate measurement.

For two bonding points for the destructive lead strains test of the two bonding points on the same surface level: a semicircle metal lift hook is placed on go between between two solder joints on, again with being no more than vertical the drawing of constant speed that per second 2 restrains.Fig. 1 is the lead strain test situation of two bonding points at same surface level.Suppose two bonding point B ₁, B ₂Between distance be C, measurement point E is X apart from the distance of first bonding point, the power that drag hook is given is F and resolves into two component F along the direction of bonding wire ₁And F ₂, F and F ₁, F ₂Angle (acute angle) be respectively θ ₁, θ ₂According to the power resolution principle as can be known, has only as X when to equal C/2 be test point in the middle of two bonding points θ ₁=θ ₂, F ₁=F ₂As X during less than C/2, θ ₁＜θ ₂, F ₁＞F ₂As X during greater than C/2, θ ₁＞θ ₂, F ₁＜F ₂Suppose F _MBe the pulling force maximal value that lead-in wire can bear, can obtain the partitioned representation formula of suspension hook tensile force f thus:

$\left\{\begin{array}{ccc}F=\frac{C}{C-X}{F}_M\cos \left(\mathrm{\&theta;}1\right)& 0\&le;X\&le;\frac{C}{2}& ---\left(1\right)\\ F=\frac{C}{X}{F}_M\cos \left(\mathrm{\&theta;}2\right)& \frac{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}{2}\&le;X\&le;C& ---\left(2\right)\end{array}\right.$

Suppose wire length be kC (k＞1) then (1), (2) formula can be changed into:

$\left\{\begin{array}{ccc}F=F_{M}C\frac{\sqrt{k^2-1}\sqrt{(k^2-1){\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}^2+4\mathrm{CX}-4X^2}}{(k^2-1){\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}^2+(3-k^2)\mathrm{CX}-2{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">X</figure-callout>}}^2}& 0\&le;X\&le;\frac{C}{2}& ---\left(3\right)\\ F=F_{M}C\frac{\sqrt{k^2-1}\sqrt{(k^2-1){\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}^2+4\mathrm{CX}-4X^2}}{({\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">k</figure-callout>}}^2+1)\mathrm{CX}-2X^2}& \frac{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}{2}\&le;X\&le;C& ---\left(4\right)\end{array}\right.$

The size of X and k value all can influence the size of measured value F as can be seen from formula (3), (4).Measurement point X should be in the centre and the wire length of lead-in wire in theory

Like this could warranty test in the process lead-in wire on suspension hook and its both sides all be 120 degree angles, guarantee that the power that applies and the suspension hook both sides suffered pulling force that goes between equates.Yet in actual mechanical process, operating personnel only rely on the position that suspension hook is placed in range estimation, make it greatly about the central authorities that go between, and wire length may not be

Will cause the deviation between the actual stretching resistance value of measured value and lead-in wire like this.Shown in Fig. 1 dotted line, in same suspension hook position, because the tinsel wire length increases, the θ angle reduces, and then can cause the increase of test value F.

For the test of the two bonding point lead strains on same surface level, as shown in Figure 2, suppose that wire length is k for two bonding points, the difference in height of two bonding points be h and $k>\sqrt{1+\frac{h^2}{{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A2009100237280008H1.png,A2009100237280008H3.png"\; state="\{\{state\}\}">C</figure-callout>}}^2}},$ Then the expression formula of tensile force f is:

$\left\{\begin{array}{ccc}F=\frac{C\cos \left(\mathrm{\&theta;}1\right)+h\sin \left(\mathrm{\&theta;}1\right)}{C-X}{F}_M& 0\&le;X\&le;\frac{1}{2}(C-\frac{h}{\sqrt{k^2-1}})& ---\left(5\right)\\ F=\frac{C\cos \left(\mathrm{\&theta;}2\right)-h\sin \left(\mathrm{\&theta;}2\right)}{\mathrm{<figure-callout\; id="1"\; label="X\; F\; M"\; filenames="A2009100237280009H1.png,A2009100237280009H2.png"\; state="\{\{state\}\}">X</figure-callout>}}{F}_M{}_{}& \frac{1}{2}(C-\frac{h}{\sqrt{k^2-1}})\&le;X\&le;C& ---\left(6\right)\end{array}\right.$

Ideal situation is that the lead-in wire on suspension hook and its both sides all is 120 degree angles naturally, makes test value F and the both sides suffered tensile force f that goes between ₁, F ₂Equate.Yet can know by analysis to have only as test point E and exist $X=\frac{1}{2}(C-\frac{h}{\sqrt{k^2-1}})$ The time suspension hook and its both sides lead-in wire angulation are equated, and therefrom as can be seen its X value change along with the variation of the size of k value.Thereby in actual measurement, can make the position of the measurement point E that suspension hook and its both sides lead-in wire angulation equate be difficult to assurance, because it no longer is the mid point of two bonding point horizontal levels.

Summary of the invention

The objective of the invention is to overcome the shortcoming of the tensile test of existing pair of bonding point, provide a kind of destructive lead-in wire of two bonding points bonding tensile test of can avoiding owing to suspension hook is difficult for becoming 120 ° of measuring error of bringing between any two with lead-in wire, thereby record bond strength more accurately, the quality of para-linkage can be carried out the method for testing of the bond strength of materials of objective analysis more.

For achieving the above object, the technical solution used in the present invention is: the mode that adopts singly-bound chalaza lead-in wire bonding tensile test, promptly be that the bonding test lead is fastened on the clamp tool, lift the clamp tool by strain gauge or tautness meter and drawing the bond strength that obtains bonding point with the constant speed that is no more than the 2g per second on vertical on the bonding point.

Clamp tool of the present invention lower end offers a groove, the bonding test lead by glue in the groove of clamp tool;

Offer a pore in the clamp tool, the bonding test lead tightens fixing by the rubber nut after passing this pore;

The clamp tool adopts the aluminium sheet of two blocks of band rubber, clamps the bonding test lead by the aluminium sheet of two blocks of band rubber and then the aluminium sheet of two blocks of band rubber is fixed.

The present invention is different from the destructive lead-in wire of the two bonding points bonding tensile test suspension hooks that have employing now and hangs over the middle method of testing of lead-in wire, adopt the mode of the destructive lead-in wire of singly-bound chalaza bonding tensile test, independent measurement bonding point one and bonding point two just can directly read pulling force numerical value on tautness meter.

Description of drawings

Fig. 1 is that two bonding points are at existing pair of bonding point lead strain test of same surface level synoptic diagram;

These two bonding points of Fig. 2 are not at existing pair of bonding point lead strain test of same surface level synoptic diagram;

Fig. 3 is the test synoptic diagram of the embodiment of the invention 1;

Fig. 4 is the test synoptic diagram of the embodiment of the invention 2;

Fig. 5 is the test synoptic diagram of the embodiment of the invention 3.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

Embodiment 1: referring to Fig. 3, the present invention adopts the mode of singly-bound chalaza lead-in wire bonding tensile test, promptly be to be fastened on the bonding test lead 2 vertical on the clamp tool 3 with the face at bonding point 1 place, clamp tool 3 lower ends offer a groove 4, bonding test lead 2 by glue in the groove 4 of clamp tool 3, thereby by strain gauge or tautness meter 5 lift clamp tool 3 on the bonding point 1 with the constant speed that is no more than the 2g per second vertical stretching being connected on read the bond strength that pulling force numerical value obtains bonding point on the tautness meter, obtain the bond strength of another bonding point by same mode.If the pulling force size that tautness meter shows is F ₁, and establish the bonding test lead and bonding point tensile strength homogeneous phase everywhere is all F ₂In case, and the stressed F of surpassing that goes between ₂, promptly to take place disrumpent feelingsly then, this moment, the value of thrust of corresponding suspension hook was the size of measured value.

Embodiment 2, referring to Fig. 4, offer a pore in the present embodiment clamp tool 3, and bonding test lead 2 passes and tightened behind this pore fixingly by the rubber nut, and its method of testing is with embodiment 1.

Embodiment 3: referring to Fig. 5, present embodiment utilizes friction force, and clamp tool 3 adopts the aluminium sheet of two blocks of band rubber, clamps bonding test lead 2 by the aluminium sheet of two blocks of band rubber and then the aluminium sheet of two blocks of band rubber is fixed, and its method of testing is with embodiment 1.

The present invention is from the pulling force of accurate measurement bond strength, for the destructive lead-in wire of two bonding points bonding tensile test, ideal situation is that the lead-in wire on suspension hook and its both sides all is 120 degree, only just identical with the suffered power of such suspension hook and two lead-in wires, the numerical value of reading by spring is only bond strength numerical value accurately like this.And in actual job, this then needs to estimate the suspension hook position so that the angle between spring and two lead-in wires becomes 120 ° between any two by the operating personnel, promptly be difficult to obtain bond strength accurately, adopt the method for testing of the destructive lead-in wire of singly-bound chalaza bonding tensile test, avoided the double lead bonding because the suspension hook position is difficult for becoming 120 ° of measuring error of being brought between any two with lead-in wire.Thereby above bonding point, record bond strength more accurately with vertical the drawing of constant speed that is no more than 2 gram per seconds.The quality of para-linkage can more objectively be analyzed.

Claims (4)

1, a kind of method of testing of bond strength of materials, it is characterized in that: the mode that adopts singly-bound chalaza lead-in wire bonding tensile test, promptly be that the bonding test lead vertical with the face at bonding point place is fastened on the clamp tool, lift the clamp tool by strain gauge or tautness meter and drawing the bond strength that obtains bonding point with the constant speed that is no more than the 2g per second on vertical on the bonding point.

2, the method for testing of bond strength of materials according to claim 1 is characterized in that: said clamp tool lower end offers a groove, the bonding test lead by glue in the groove of clamp tool.

3, the method for testing of bond strength of materials according to claim 1 is characterized in that: offer a pore in the said clamp tool, the bonding test lead tightens fixing by the rubber nut after passing this pore.

4, the method for testing of bond strength of materials according to claim 1 is characterized in that: said clamp tool adopts the aluminium sheet of two blocks of band rubber, clamps the bonding test lead by the aluminium sheet of two blocks of band rubber and then the aluminium sheet of two blocks of band rubber is fixed.

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