Catalysts for Epoxy Molding Compounds in Microelectronic

22

Downloaded by FUDAN UNIV on March 20, 2017 | http://pubs.acs.org Publication Date: March 15, 1984 | doi: 10.1021/bk-1984-0242.ch022

Catalysts for Epoxy M o l d i n g Compounds in Microelectronic Encapsulation WINSTON C. MIH California State University, Chico, CA 95929 Epoxy molding compounds encapsulate various micro electronics and represent a major part of polymer packages for semiconductors. The key to the development of the proper epoxy molding compounds for microelectronic encapsulation is the catalyst in the formulation. The many new developments in catalysts during the last few years have enabled tremendous improvements in microelectronic encap sulation. However, the exact curing mechanisms of various catalysts in epoxy molding compounds are s t i l l not fully understood. This paper in tends to review the following catalysts and their curing mecahnisms in phenolic and anhydride cured epoxy molding compounds for microelectronic encapsulation: 1) Lewis acids, e.g., stannous or zinc octoate; 2) Lewis bases, e.g., tertiary amines, phosphorous compounds, imidazoles and their salts; 3) Organometallics, e.g., metal acetyl acetonates. The concept of polymer encapsulation dates back almost to the invention of the transistor (1). To eliminate the costly hermetic seals, it was necessary to find low cost techniques that would also yield handling capability and environmental protection. Early systems had poor reliability performance and failed under the least severe environmental stress conditions (2). In 1962, polymer encapsulated transistors were produced and directed primarily at the consumer market. The major advantage of polymers was the economics of production where many parts could be packaged simultaneously with a relatively low cost material. Polymer packages were used on semiconductor devices when the cost of semiconductor packages became significant 0097-6156/84/0242-0273$06.00/0 © 1984 American Chemical Society Davidson; Polymers in Electronics ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

POLYMERS IN ELECTRONICS


274

r e l a t i v e to the o v e r a l l device c o s t . D e s p i t e s e v e r a l drawbacks such a s , m o i s t u r e p e r m e a b i l i t y , aluminum c o r r o s i o n , thermom e c h a n i c a l s t r e s s , p o o r m o l d a b i l i t y and f l o w c h a r a c t e r i s t i c s , c u r r e n t l e a k a g e , and c h a r g e e f f e c t s a t t h e s e m i c o n d u c t o r / p o l y m e r i n t e r f a c e , t h e u s e o f p o l y m e r p a c k a g e s c a u g h t on r a p i d l y and performance parameters were improved over t h e y e a r s ( 3 ) . I n the p e r i o d s i n c e 1962, the use of polymer packaged d e v i c e s h a s i n c r e a s e d f r o m p u r e l y consumer a p p l i c a t i o n s t o i n d u s t r i a l and other high r e l i a b i l i t y a p p l i c a t i o n s . The p r e s s u r e s e x e r t e d b y c o m m e r c i a l and i n d u s t r i a l u s e r s on s e m i c o n d u c t o r s u p p l i e r s h a v e s i g n i f i c a n t l y improved the r e l i a b i l i t y of the polymer encapsulated semiconductors (2). T o d a y , i t i s e s t i m a t e d t h a t n e a r l y 60% o f a l l semiconductor devices are encapsulated i n polymers (3). E l e c t r o n i c packages are s e a l e d t o prevent gross c o n t a m i n a t i o n , h a n d l i n g damage, and t h e e n t r y o f d e t r i m e n t a l g a s e s . The t e c h n i c a l s o l u t i o n w o u l d be t o use a " t r u e " h e r m e t i c p a c k a g e , i . e . , impermeable g l a s s , c e r a m i c , or m e t a l h o u s i n g . However, t h i s i s n o t f r e q u e n t l y d e s i r a b l e due t o p r o c e s s i n g c o s t s , r e w o r k d i f f i c u l t y , t e m p e r a t u r e l i m i t a t i o n s o f e n c l o s e d e l e c t r o n i c s , and p o t e n t i a l damage t o e x p e n s i v e e n c l o s e d e l e c t r o n i c s . Polymers are t h e r e f o r e c o n s i d e r e d to p r o v i d e the needed p r o t e c t i o n . P o l y m e r s u s e d f o r s e m i c o n d u c t o r e n c a p s u l a t i o n must p r o t e c t a g a i n s t t h e e n v i r o n m e n t t o w h i c h t h e d e v i c e i s l i k e l y t o be e x p o s e d , s u c h as m o i s t u r e , c h e m i c a l a g e n t s , w i d e t e m p e r a t u r e f l u c t u a t i o n s and m e c h a n i c a l s h o c k . The p o l y m e r i c m a t e r i a l must be a b l e t o do t h i s w i t h a minimum o f e f f e c t on d e v i c e p a r a m e t e r s o v e r an e x t e n d e d p e r i o d o f t i m e , and be r e l a t i v e l y i n e x p e n s i v e and e a s y t o p r o c e s s ( 4 ) . Many t h e r m o s e t t i n g p o l y m e r s h a v e b e e n u s e d , b u t o n l y e p o x i e s , s i l i c o n e s , and p h e n o l i c s h a v e b e e n u s e d e x t e n s i v e l y f o r l a r g e s c a l e p r o d u c t i o n ( 1 , 4_) . J o i n t r e s e a r c h p r o g r a m s i n t h e e a r l y 1970s b e t w e e n s e m i c o n d u c t o r m a n u f a c t u r e r s and e p o x y m o l d i n g compound s u p p l i e r s l e d t o t h e u s e o f epoxy m o l d i n g compounds as t h e m a j o r e n c a p s u l a n t s f o r s e m i c o n d u c t o r parts (3). T o d a y , e p o x y m o l d i n g compounds r e p r e s e n t a m a j o r p a r t of polymer packages f o r semiconductors. Epoxy e n c a p s u l a n t s d o m i n a t e t h e m a r k e t w i t h t h e h i g h e s t v o l u m e g r o w t h , a b o u t 15-20%, and p r o d u c t i o n i s e s t i m a t e d a t s e v e r a l b i l l i o n u n i t s p e r y e a r . The u s e o f s i l i c o n e s i s d e c l i n i n g and p h e n o l i c s a r e e s s e n t i a l l y out of the market ( 3 ) . Epoxy C u r i n g M e c h a n i s m The k e y t o t h e d e v e l o p m e n t o f t h e p r o p e r epoxy m o l d i n g compounds f o r m i c r o e l e c t r o n i c encapsulation i s the c a t a l y s t i n the formulation. I n s p i t e of s e r i o u s l i m i t a t i o n s i n epoxy m o l d i n g compound p e r f o r m a n c e i n s e n s i t i v e m i c r o e l e c t r o n i c d e v i c e s a b o u t t e n y e a r s a g o , t h e many new d e v e l o p m e n t s i n c a t a l y s t s d u r i n g t h e l a s t few y e a r s h a v e e n a b l e d tremendous i m p r o v e m e n t s . However, t h e e x a c t c u r i n g mechanisms o f v a r i o u s c a t a l y s t s i n e p o x y m o l d i n g compounds a r e s t i l l n o t f u l l y u n d e r s t o o d t o d a y .

Davidson; Polymers in Electronics ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

22.

MIH

Catalysts for

Epoxy Molding

Compounds

275


The r o l e o f c a t a l y s t s i n epoxy m o l d i n g compounds f o r m i c r o e l e c t r o n i c s i s i n i n i t i a t i n g i o n i c p o l y m e r i z a t i o n , and s u b s e q u e n t l y , c r o s s l i n k i n g of p h e n o l i c o r a n h y d r i d e h a r d e n e r s w i t h epoxy prepolymers at the proper molding c o n d i t i o n s . This i s achieved e i t h e r through homopolymerization orh e t e r o p o l y m e r i z a t i o n , d e p e n d i n g upon t h e t y p e o f c a t a l y s t and c u r i n g mechanism. The i d e a l c r o s s l i n k e d t h r e e - d i m e n s i o n a l n e t w o r k c a n t h e n be r e a c h e d t o p r o v i d e t h e epoxy m o l d i n g compound w i t h t h e p r o p e r m o i s t u r e r e s i s t a n c e , p h y s i c a l , e l e c t r i c a l , and e l e c t r o n i c p r o p e r t i e s , and s h e l f s t a b i l i t y f o r t r a n s p o r t a t i o n and s t o r a g e . A n h y d r i d e C u r e d Epoxy R e a c t i o n M e c h a n i s m . In the case of a n h y d r i d e c u r e d epoxy r e a c t i o n , c a t a l y s t s w i l l p r o m o t e r i n g opening of t h e a n h y d r i d e t o p r o v i d e c a r b o x y l i c group f o r r e a c t i o n w i t h e p o x i d e . W i t h o u t c a t a l y s t s , t h e r e a c t i o n s a r e s l o w and accompanied by e x t e n s i v e e p o x i d e h o m o p o l y m e r i z a t i o n a t e l e v a t e d temperatures. I n t h e n o n - c a t a l y z e d a n h y d r i d e c u r e d epoxy r e a c t i o n , T a n a k a and K a k i u c h i C5, 6) f o u n d t h a t t h e r e a c t i o n r a t e was p r o p o r t i o n a l t o t h e c o n c e n t r a t i o n o f e p o x i d e , a c i d a n h y d r i d e , and h y d r o x y l compound, s u g g e s t i n g a t e r m o l e c u l a r t r a n s i t i o n s t a t e f o r t h e r a t e determining step.

R The r e a c t i o n c o u l d be p r o m o t e d by e l e c t r o n - w i t h d r a w i n g s u b s t i t u e n t s on t h e h y d r o x y l g r o u p s , i n d i c a t i n g h y d r o g e n b o n d i n g w i t h epoxide. F o r L e w i s b a s e and L e w i s b a s e s a l t c a t a l y z e d a n h y d r i d e c u r e d e p o x y r e a c t i o n s , F i s c h e r (7) p r o p o s e d t h a t t h e i n i t i a l s t e p o f an a n h y d r i d e , e p o x i d e , and t e r t i a r y amine s y s t e m was t h e a c t i v a t i o n of the anhydride ( r e a c t i o n 1):


276


0 1 V

V ' Τ

C

\ 0

+

:NR

»

3

\/Cx I

OH

0 R N:


3

+

>

ROH

0

(3)

OR

+

R|N:H

®0R

(4)

0 CH

OH

-CH—CH R'

2

2

Ο

X

II

Cv OR

(5)

Ç—0CH —ÇH-CH —R 2

1

2

OH (ROH c a n be f r e e

acid present

as a n i m p u r i t y i n t h e

anhydride.)

S o r o k i n concluded t h a t the f o r m a t i o n of the amine-anhydride c o m p l e x (as p r o p o s e d by F i s c h e r ) d i d n o t h a v e a d e c i s i v e i n f l u e n c e on t h e r a t e d e t e r m i n i n g s t e p , a l t h o u g h i t was an i n t e r m e d i a t e i n t h e c a t a l y t i c s o l v o l y s i s of t h e a n h y d r i d e . F e l t z i n , e t . a l . (10) i n d i c a t e d t h a t t h e i n i t i a l s t e p i n t h e r e a c t i o n was c a t a l y s t a c t i v a t i o n by t h e r e a c t i o n o f t h e t e r t i a r y amine w i t h a c o - c a t a l y s t t o f o r m a q u a t e r n a r y s a l t . F i s c h e r s u p p o r t s t h e F e l t z i n mechanism b e c a u s e he r e p o r t s t h a t q u a t e r n a r y s a l t s c a t a l y z e t h e r e a c t i o n i n much t h e same way a s t e r t i a r y amines. T a n a k a a n d K a k i u c h i (8) a l s o f a v o r a c a t a l y s t activation. I t c a n be c o n c l u d e d t h a t t h e e x p e r t s e s s e n t i a l l y a g r e e t h a t t h e mechanism c o n s i s t s o f : (a) C a t a l y s t (or a c t i v a t e d c a t a l y s t ) r e a c t i n g (or s o l v a t i n g the anhydride) to generate a c a r b o x y l a t e . (b) The g e n e r a t e d c a r b o x y l a t e r e a c t i n g w i t h t h e e p o x i d e t o g e n e r a t e an a l k o x i d e . (c) The g e n e r a t e d a l k o x i d e r e a c t i n g w i t h t h e a n h y d r i d e , e t c . H o w e v e r , M i k a (11) f o u n d t h a t i n m i x i n g h i g h l y p u r i f i e d a n h y d r i d e and t e r t i a r y a m i n e , t h e r e i s no e v i d e n c e f o r t h e f o r m a t i o n o f t h e c o m p l e x p r o p o s e d by F i s c h e r o r T a n a k a . T h i s was b a s e d on n u c l e a r m a g n e t i c r e s o n a n c e s p e c t r a c o m p a r i n g i m i d a z o l e w i t h an e q u i m o l a r m i x t u r e of i m i d a z o l e and n a d i c m e t h y l a n h y d r i d e .


278



R e c e n t l y , C r a n d a l l and M i h (12) s t u d i e d t h e a n h y d r i d e c u r i n g mechanism u s i n g n e a r a n d m i d d l e I R and D S C T h e i r f i n d i n g s s u p p o r t e d t h e a n h y d r i d e - e p o x i d e c u r i n g mechanism t h a t most e x p e r t s e s s e n t i a l l y agree upon. P h e n o l i c C u r e d Epoxy R e a c t i o n M e c h a n i s m . A n i m p o r t a n t f a c t o r i n the epoxy-phenolic r e a c t i o n i s the degree of r e a c t i o n of the u n r e a c t e d e p o x i d e group w i t h t h e g e n e r a t e d s e c o n d a r y h y d r o x y l groups of the h y d r o x y l - a l k y l products (13). I n order to have optimum m e c h a n i c a l and e l e c t r i c a l p r o p e r t i e s , t h e p h e n o l i c c u r e d e p o x y s h o u l d be f o r m u l a t e d t o h a v e s t o i c h i o m e t r i c q u a n t i t i e s o f t h e epoxy and p h e n o l i c . Epoxy-phenolic r e a c t i o n s which proceed w i t h o u t t h e r e a c t i o n of the secondary h y d r o x y l group a r e s é l e c tive reactions. The d e g r e e o f s e l e c t i v i t y o f r e a c t i o n w i l l depend on t h e p h e n o l i c u s e d , c a t a l y s t s , t e m p e r a t u r e and o t h e r r e a c t i o n v a r i a b l e s . N o n s e l e c t i v e r e a c t i o n of the generated secondary h y d r o x y l group can upset s t o i c h i o m e t r y i n the epoxyp h e n o l i c r e a c t i o n , and t h u s r e d u c e p r o p e r t i e s . A l v e y (13) s t u d i e d a s e r i e s of n i t r o g e n c o n t a i n i n g Lewis base c a t a l y s t s i n t h e p h e n o l i c c u r e d epoxy s y s t e m t o show s e l e c t i v i t y and reactivity. S h e c h t e r and W y n s t r a (14) s t u d i e d the uncatalyzed p h e n o l i c c u r e d e p o x y r e a c t i o n and p r o p o s e d t h e f o l l o w i n g m e c h a n i s m , (with reaction 1 predominating):

(I) OH

+

CH —CH—CH —OR 2

2

(2)

H —CH—CH —OR 2

2

OH


22.

MIH

Catalysts for Epoxy Molding

279

Compounds

The s t r o n g b a s e c a t a l y z e d p h e n o l i c c u r e d epoxy r e a c t i o n p r o c e e d s v i a the phenoxide i o n which r e a c t s w i t h epoxide, generating t h e alkoxide ion. The h i g h b a s i c i t y o f t h e a l k o x i d e i o n r e a c t s w i t h p h e n o l i c t o r e g e n e r a t e t h e p h e n o x i d e i o n and t h e r e a c t i o n r e p e a t s itself.

°

H

+

k

o

h

—

^5^-Ο + Κ

>

Θ

+ H O

Θ

2

PHENOXIDE ION


0

θ

+

CH —CH—CH„—OR 2

0

θ

^Q^-O-CHg—CH—CH -OR 2

A L K O X I D E ION

ο ^O^-

θ

0—CH -CH-CH -0R

^Q^—

2

2

+

0 — C H — C H — C H — OR 2

2

^Q^—

Η-

OH

( ^ ) ~ °

Θ

The n i t r o g e n - c o n t a i n i n g L e w i s b a s e b e n z y I d i m e t h y l a m i n e was f o u n d to be a b e t t e r c a t a l y s t than potassium hydroxide. Furthermore, e v i d e n c e shows t h a t t h e q u a t e r n a r y compound o f b e n z y l d i m e t h y l amine was e v e n a b e t t e r c a t a l y s t ( 1 4 ) . The p h e n o l i c c u r e d epoxy r e a c t i o n i s a f i r s t o r d e r k i n e t i c s . The f o l l o w i n g L e w i s b a s e s have been used a s c a t a l y s t s f o r t h e e p o x y - p h e n o l i c r e a c t i o n ( 1 5 ) : (a) I n o r g a n i c bases (16) (b) N i t r o g e n bases (17) (c) Ammonium s a l t o f s t r o n g a c i d s ( 1 8 ) (d) H e t e r o c y c l i c s , such as i m i d a z o l e o r t r i a z o l e (19) (e) A l k a n o l a m i n e (20) R e c e n t l y , p h o s p h i n e compounds h a v e b e e n u s e d a s c a t a l y s t s i n the epoxy-phenolic o r epoxy-anhydride r e a c t i o n s . There i s i n d i c a t i o n t h a t t h e mechanism does n o t i n v o l v e t h e d e c o m p o s i t i o n o f t h e phosphonium compound t o t h e f r e e p h o s p h i n e s p e c i e s . T h e


280


i n i t i a t i o n mechanism p r o b a b l y i n v o l v e s t h e f o r m a t i o n o f h y d r o g e n bonded p h o s p h o n i u m - e p o x y o r p h o s p h o n i u m - a n h y d r i d e c o m p l e x e s t h a t rearrange w i t h heat a p p l i c a t i o n to form a c t i v a t e d species r e s u l t i n g i n t h e p o l y m e r i z a t i o n o f t h e e p o x y - a n h y d r i d e components (21). M i k a (22) p r o p o s e d t h e c o m p l e x i n t e r m e d i a t e s i n t r i a r y l phosphine c a t a l y s i s a s :


0

M i k a (22) a l s o p r o p o s e d t h a t s a l t s o f t e r t i a r y amine o r p h o s phonium complexes a r e not a d i s s o c i a t i o n ( r e a c t i o n 1 ) , b u t a p u s h - p u l l concerted e f f e c t . R PY

R P:

'

3

3

+

Y

(I) OR

R N:Y '

R M:

3

3

+

Y

S*

.0*

R P:. 3

\ S Y

There i s c o n s i d e r a b l e evidence f o r the p u s h - p u l l concerted e f f e c t i n t h e r e a c t i o n mechanism by u s i n g l e a d s a l t s and DMP-30 s a l t s a s c a t a l y s t s i n t h e p h e n o l i c c u r e d epoxy r e a c t i o n . The complex f o r m a t i o n i s a l s o s u p p o r t e d by A l v e y (13) and Son ( 2 3 ) . The a c i d c a t a l y z e d r e a c t i o n o f e p o x y - p h e n o l i c h a s n o t b e e n s t u d i e d i n d e t a i l . O x i d i z e d s t a n n o u s a c y l a t e (24) and o t h e r


22.

MIH

Catalysts for Epoxy Molding

Compounds

281

s t a n n o u s s a l t s (25) h a v e b e e n u s e d . From t h e e x p e r i m e n t a l r e s u l t s a v a i l a b l e , stannous s a l t s have been found t o be p a r t i c u l a r l y u s e f u l f o r p h e n o l i c c u r e d c y c l o a l i p h a t i c epoxy s y s t e m s ( 2 5 ) . Catalysts


From t h e u p - t o - d a t e l i t e r a t u r e a n d p a t e n t r e v i e w o f c a t a l y s t s u s e d i n a n h y d r i d e and p h e n o l i c c u r e d e p o x y m o l d i n g compounds, i t i s e v i d e n t t h a t i m i d a z o l e s and t h e i r d e r i v a t i v e s predominate (Table I ) . M e t a l complex, t r i a l k y l or t r i a r y l p h o s p h i n e s a n d t h e i r c o m p l e x e s , L e w i s a c i d s s u c h as z i n c o r s t a n n o u s o c t o a t e a r e u s e d t o a much l e s s e r e x t e n t ( T a b l e I I ) . T h e r e a r e a few e x a m p l e s o f t e r t i a r y amines and u r e a d e r i v a t i v e s used. Table I .

L e w i s B a s e and L e w i s B a s e S a l t C a t a l y s t s

C a t a l y s t s Used Lewis Base: Imidazole 2-heptadecylimidazole I m i d a z o l e 16 4-methyl-2-phenylimidazole 2-ethyl-4-methylimidazole 1- ( 2 - h y d r o x y - 3 - p h e n o x y p r o p y l ) i m i d a z o l e 2-methylimidazole 2-phenylimidazole Organic Phosphine Triphenylphosphine Urea D e r i v a t i v e s Latent sources of dimethylamine

Refs.

26 27 28 29,30 31 32 33 34 35

L e w i s Base S a l t : Q u a t e r n a r y phosphonium s a l t s T e t r a h y d r o c a r b y l phosphonium phenoxide s a l t s B u t y l tri-phenylphosphonium s a l t of 2,2 ,6,6 -tetrabromobisphenol A Phenylphosphonium t e t r a p h e n y l b o r a t e Carbon d i s u l f i d e - t r i c y c l o h e x y l p h o s p h l n e adduct f

Table I I .

21 36 36 37,38 33,39

1

O r g a n o m e t a l l i c and L e w i s A c i d C a t a l y s t s

C a t a l y s t s Used

Refs.

Organometallic: Tetrakis(acetylacetonato)zirconium Bis(acetylacetonato)dipyridine cobalt Lewis A c i d : Z i n c or stannous octoate


40 41 42


282


The mechanism for organometallies and Lewis acids in phenolic or anhydride cured epoxy molding compounds are s t i l l not fully understood. Lewis bases such as imidazoles can be reacted with organic acids to form salts in order to improve latency. Imidazoles are, so far, the most widely accepted as a compatible catalyst family for encapsulating microelectronics. Generally speaking, catalytic activity should correlate with electron density at the azole nitrogen of the imidazole structure. In addition, the basicity of a given imidazole may determine its corrosivity towards aluminum and, hence, its microelectronic compatibility. Triaryl and triallyl phosphine complex catalysts are gradually growing in usage and have shown potential for future development in terms of latency and excellent microelectronic compatibility. Further studies are required before the reaction mechanism can be understood more fully. Literature Cited 1. Reich, B. Solid State Technology Sept. 1978, 82. 2. Reich, B.; Hakim, Ε. B. Microelectronics and Reliability 1976, 15, 29. 3. Woodard, J. B. Preprints. Society of Plastics Engineers 4th Annual PACTEC. Jan. 31-Feb. 2, 1979, p. 89. 4. Olberg, R. C. J. Electrochem. Soc. 1971, 118(1), 129. 5. Tanaka, Y.; Kakiuchi,H. J. Macromol. Chem. 1966, 1, 307. 6. Tanaka, Y.; Kakiuchi, H. J. Polym. Sci. 1964, A2, 3405. 7. Fischer, R. F. J. Polym. Sci. 1960, 44, 155. 8. Tanaka, Y.; Kakiuchi, H. J. Appl. Polym. Sci. 1963, 7, 1063. 9. Sorokin, M. F. Lakokrasoch. Mater. Ikh. Primen 1967, 5, 67. 10. Feltzin, J. J. Macromol. Sci. Chem. 1969, A3, 261. 11. Mika, T., personal communication. 12. Crandall, E. W.; Mih, W. C. Preprints. American Chemical Society Div. Org. Coatings Plast. Chem. Sept. 1982, 47, 592. 13. Alvey, F. B. J. Appl. Polym. Sci. 1969, 13, 1473. 14. Shechter, L.; Wynstra, J. Ind. and Eng. Chem. 1956, 48(1),86. 15. May, C. Α.; Tanaka, Y. "Epoxy Resins: Chemistry and Technology"; Dekker: New York, 1973; Chap. 4. 16. Dynamit Nobel. German Pat. 1,184,496. 17. Aba, Ltd. Netherlands Pat. Appl. 246,535, 18. Berlanger, W.; Cooke, H. G. (to Devoe and Raynolds Co.) U.S. Patent 2,928,803. 19. Union Carbide Corp. Netherlands Pat. Appl. 6,512,268. 20. Ephraim, S. N. (to Reichhold Chemical). U. S. Pat. 3,264,369. 21. Smith, J. D. B. Preprints. American Chemical Society Div. Org. Coatings and Plast. Chem. Sept. 1978, 39, 42. 22. Mika, T., personal communication. 23. Son, P. N.; Weber, C. D. J. Appl. Polym. Sci. 1973, 17,1305. 24. Proops, W. R. (to Union Carbide). U. S. Pat. 3,284,383.



22. MIH

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25. Proops, W. R.; Fowler, G. W. (to Union Carbide). U. S. Pat. 3,117,099. 26. Morton-Norwich Products, Inc. Japanese Pat. 82 49 647, 1982; Chem. Abstr. 1982, 97, 39874r. 27. Trautmann, H.; Schillgalies, J.; Martin, M.; Krausche, C.; Eckhardt, I.; Reichardt, L. Ger.(East) DD 154 824, 1982; Chem. Abstr. 1982, 97, 164100m. 28. Nitto Electric Industrial Co., Ltd. Japanese Patent 82 59 365, 1982; Chem. Abstr. 1982, 97, 93634a. 29. Segawa, T.; Suzuki, H.; Kitamura, M.; Numata, S.; Nishi, K. Ger. Offen. DE 3 137 480, 1982; Chem. Abstr. 1982, 97, 7395u. 30. Mitsui Toatsu Chemicals, Inc. Japanese Patent 81 127 625, 1981; Chem. Abstr. 1982, 96, 53239y. 31. Lyalyushko, Κ. Α.; Sorokin, M. F.; Sigunova, O. V. Tr.-Mosk. Khim.-Tekhnol. Inst. im. D. E. Mendeleeva 1980, 110, 76; Chem. Abstr. 1982, 96, 182808g. 32. Ricciardi, F.; Joullie, M. M.; Romanchick, W. Α.; Griscavage, A. A. J. Polym. Sci., Polym. Letter Ed. 1982, 20(2), 127; Chem. Abstr. 1982, 96, 105153n. 33. Toshiba Corp. Japanese Patent 82 24 553, 1982; Chem. Abstr. 1982, 97, 57259y. 34. Ikeya, H.; Suzuki, H.; Oguni, T.; Matsumoto, K.; Hatanaka, Α.; Wada, M. Eur. Pat. Appl. EP 41 662, 1981; Chem. Abstr. 1982, 96, 114563y. 35. LaLiberte, B. R.; Sacher, R. E.; Bornstein, J. Report 1981, AMMRC-TR-81-30; Chem. Abstr. 1982, 96, 123843s. 36. Doorakian, G. Α.; Bertram, J. L. U. S. Patent 4 302 574, 1981; Chem. Abstr. 1982, 96, 86422f. 37. Hitachi Chemical Co., Ltd. Japanese Patent 81 84 717, 1981; Chem. Abstr. 1981, 95, 170427y. 38. Suzuki, H.; Sato, M.; Muroi, T.; Watanabe, Y. Preprint. SPE 19th ANTEC, 1973, p. 6. 39. Toshiba Corp. Japanese Patent 82 23 626, 1982; Chem. Abstr. 1982, 96, 218787r. 40. Toshiba Corp. Japanese Patent 82 51 720, 1982; Chem. Abstr. 1982, 97, 56707f. 41. Shukla, A. K.; Karkozov, V. G.; Nikolaev, A. F.; Vinogradov, M. V. Plast. Massy 1982, 5, 20; Chem. Abstr. 1982, 97, 24629r. 42. Takahama, T.; Geil, P. H. Makromol. Chem., Rapid Commun. 1982, 3(6), 389; Chem. Abstr. 1982, 97, 56602t. RECEIVED September 2,

1983


Catalysts for Epoxy Molding Compounds in Microelectronic

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